Ear cheese is a term used often for the accumulation of dead skin cells around a stretched earlobe piercing. Switching to organic jewelry, as well as regular cleaning can help solve or greatly reduce this problem.
No one wants to give someone a hug and then hear "Do you smell something dead?"
On that note, if you really want to play a nasty trick on a friend, remove your ear jewelry, wipe the inside edges of the piercing with a finger, and then wipe said finger under your friend's nose. Be warned that they may not be your friend for very long!