Squeezing grapes and olives is a melacha called Mefarayk. You are not allowed to drink any juice that comes out from them on Shabbos – even juice that leaked out on its own. You might come to squeeze out more. (ShA 1 – MB 1, 3)
All other fruits are normally for eating. However, those fruits which are used by some people for their juice – like berries, apples and pomegranates – are ossur d’rabbonon to squeeze. Juice of such fruits that leaked out on its own is ossur to drink. But if you collect the fruit for eating, you are allowed to drink their juice that leaked on Shabbos. (ShA 1 – MB 5, 6, 9)
There is a third category of fruit – those fruits that no one uses them for their juice. You are allowed to squeeze the juice out of them . We view the liquid as solid food – so you are merely separating one part of the fruit from the other part (like cutting). (ShA 1 – MB 7)
Let's say we are informed about people somewhere who have an abundance of a certain fruit. Because of it, these people are using the fruit for their juice. We are now not allowed to squeeze these fruits no matter where in the world we live. An example is pears in Germany . (MB 8)
You are allowed to suck any food that has liquid inside it with the exception of grapes and olives. But even grapes and olives may be placed into your mouth to suck out their juice. Afterwards you can throw out the solids. (MB 12)
Squeezing out fruit juice directly onto food is permitted. The juice has a halacha of solid food in this case. But do not squeeze the juice into another liquid. There is an important minority opinion that holds not to squeeze juice even directly onto food. You will get a beracha for being machmir. (ShA 4 – MB 17 – BeH ”haboh”)
Do not squeeze juice out of inedible (unripe) fruit. It’s Borer and therefore ossur even when the liquid drops directly onto food. (ShA 5 – MB 20, 21)
You can make fresh lemonade on Shabbos by squeezing the juice onto dry sugar first. Then mix the lemon-sugar solution into water. (MB 22)
If a pickle is too water-logged, you can squeeze out the juice so the pickle will be tastier to eat. Even if the juice collects into a dish, your intention is not for the juice. Another example of this is noodles that are too oily. You may squeeze out the oil for the sake of the noodles. (These cases are muttar only for eating the food on Shabbos.) (ShA 7 – MB 24, 25, 26)
You are allowed to chop off a piece from a block of ice. However, chopping the ice to change it into liquid is ossur because of Molid. You should be machmir not to chop it even when there is already liquid in the container holding the ice. (ShA 9 – MB 32 – ShaH Siman 318:146)
You are also allowed to put ice into a warm drink. There is no maaseh of melting, and the melted ice is not apparent. (ShA 9 – MB 34)
What if the melting happens by itself but the new liquid **is** apparent.? For example, to take congealed gravy out to the warm sun. The Shulchan Aruch allows this as well, however the Rama 318:16 says to be machmir unless you need it. (MB 35)
If a layer of ice forms over a container of water, you are allowed to break it. If you need the water for Shabbos, you may even break river-ice or well-ice to get the water underneath. (ShA 10 – MB 36)
Washing with very icy water could lead to crushing the ice with your hands. Wash, but be careful not to crush. (MB 37)
As we said by ice, you are allowed to put salt into warm liquid, even though it will melt. (MB 38)
You are allowed to press down on snow as you walk. Chazal weren’t goizer against the inevitability of melting the snow in this difficult situation. (ShA 13 – MB 39)
Urinating in the snow causes the snow to melt by means of a maaseh. Avoid it if there is no bother.(ShA 14 – MB 40)
Are you allowed to use a wet sponge on Shabbos? Yes, under two conditions: (1) the sponge has a handle and (2) no pressing – only wiping. (ShA 17 – MB 55)
The Shulchan Aruch holds like the Rishonim that maintain – p’sik raysha d’lo nicha lay is ossur d’rabbonnon on Shabbos. But you can be lenient if the situation has another tzad hetter. (ShA 18 – BeH “yaysh”)
P’sik raysha d’lo nicha lay applies not only when you **don’t like** the inevitable melacha, but even when you **don’t care** (you don’t benefit) about the inevitable melacha.(BeH “d’lo”)
The Shulchan Aruch holds that squeezing out liquids other than water falls under Mefarayk and not Melabayn. Therefore one is chayav only when squeezing to use the liquid. Squeezing out water (or white wine – Ta”z) is Melabayn as well. If a drink spills on the tablecloth gently scrape off the surface liquid with a knife. Beware of two things: (1) don’t press down to avoid S’chitta and (2) don’t spread the drink onto parts of the cloth that are not yet stained. If water spills on the cloth, you certainly must be careful because of the added issur of Melabayn. (MB 55)
Wringing out hair is ossur d’rabbonon. If you toivel on Shabbos, make sure not to squeeze out your hair in order to dry it. (MB 55)
You are allowed to spice your food and flavor your drink even though the food/drink changes color. Some poskim even allow you to color your food intentionally, but it’s best to avoid this. (ShA 19 – MB 56)
If wiping your dirty hands on a cloth will for sure stain it, it’s ossur. Some poskim are maykil because it’s derech lichlooch. You can rely on them when you’re stuck. (ShA 20 – MB 57,59)
It’s okay to stain your fingers and lips while eating berries -”ain tz’via ella b’dovor shedarko litzvoa”.(MB 38)