Assign one t-shirt from the team to be a ‘free t-shirt’. In other words it can get as dirty as you like but it won’t count.
Team line up and a t-shirt is selected secretly. One team member is blindfolded and has to write something big, or something is poured over the t-shirt of their choice. Other team members cannot indicate in any way. If they select correct t-shirt then this t-shirt can be used as a ‘free t-shirt’ over the rest of the game.
If they guess wrong – oh dear.
Needed: marker pens, gunge, t-shirts, blindfold