T-shirt ideas?

We're screenprinting t-shirts for my graphics class, and I wanted some clever, funny, or cool ideas for one of my t-shirts. The teacher is pretty lenient with letting us print what we want (for example, one of my shirts has a mushroom and the word "fungus" on it) AS LONG as it's not blatant.

I'm not good at coming up with ideas so can someone help me out?