Immunities

Whenever my children do something overly disgusting, like eating random candy off the ground, I always say,"Oh well, they are just building their immunities." I'm pretty sure I did the same disgusting things when I was a child. So my question is, where are my immunities? I think I must have misplaced them along the road to adulthood. I looked under the couch, but all I found was a partially eaten sucker stuck to the carpet. No immunities there. I looked in the kitchen sink, but just found a pile of dirty dishes. I looked under my bed, but I just found dust bunnies. So then I tried to think of the place in the house where one might collect the most amount of immunities and I thought of the bathroom. So I ran in and looked in the sink, but there were just smudgy chocolate handprints. I looked in the toilet and just found, well...use your imagination there. (ewwwww) So here I sit, immunity-less, coughing, sniffing and wondering why all those built up immunities aren't doing me any good!! If you find them, could you let me know?