The egg carton drives me nuts!!!

Okay, we all know that C is close to perfect (insert slight sarcasm ;)  ), but he has this interesting habit with the carton of eggs in the fridge.  I've always thought it was normal to use an egg and then throw the shell in the garbage, well, C does not throw the empty shells in the garbage, he puts them back in the carton! Urgh!  Does he want to count the empty shells to ensure that we used the full dozen??  I just can't understand the reason behind this habit...

Anyone else have this issue at home???