I rarely restrain from cracking in public. Sometimes in a quiet place with other people, it's fun to try and get some echo.
When I worked in the 'count room' of a casino, the other cashiers and even surveillance staff (there were lots of cameras) became used to me bending over trolleys/tables and hanging off various things to crack my back. Quite often I'd stop work to stretch my back, or bob down to pop my knees. Cracking knuckles was banned at lunch break though…