Other oddities...

Go to 7-Eleven and buy a hot dog (where the clerk takes a frank from the spinning petri dish and puts it in a bun) and you pay tax. Grab a frozen burrito and nuke it in the store's microwave and you don't pay tax. In both cases, you've walked out of the store with hot, prepared food.

Go to a nursery and buy a rose bush and a lemon tree. The rose is taxed, the lemon is not.