Both of the words 'go' and 'pot' have so many meanings that it is difficult to provide a straightforward answer.
For example, a group of friends may go out drinking regularly and usually create a 'kitty'...ie a money-collection or pot...to pay for their entertainment. A member of the group might say, "When we meet, we each take out a �10.00 note and that has to go in a pot."
A pot may also refer to a receptacle, often kept under a bed, for someone to urinate in during the night. The verb 'go' also may mean 'urinate', so the person may say, "I'm unable to get to the toilet so at night I have to go in a pot."
There are many other possibilities. Perhaps you can tell us the circumstances in which you have seen the words.