I just shaved off my beard in one go and didn't leave a funny handlebar/little moustache on to walk around my cell with for a few hours.
Just didn't care anymore, just didn't care.
If this ever happens to you, don't suffer in silence, there are people out there you can talk to. Not to me, I'm not actually interested in anyones problems other than my own, but some people are happy to listen to any old shite. Talk to them.