Once I had an argument with a creationist about, well, the origin of the species. This particular guy would not just refuse to accept scientific facts but wasn't even ready to listen to a counterpoint to his argument and wasn't ready to even recognize that there might be people who have a different point of view other than his. In the end, enraged, he sneered:
"If humans evolved from apes or monkeys, how come we don't see monkeys turn into humans everyday?"
I replied: "Well, you are wrong. That does happen regularly. In fact, I am speaking to one such right now."
Maybe I should've said it the other way around. But it worked :)
PS: Humans did not evolve from apes/monkeys, but we split from a common ancestor millions of years ago. We are two different branches. Cousins, if you will.