16-17 Year Old Trick or Treaters

I was talking with one of my neighbors earlier. We just moved to the neighborhood a few months ago from out of state, and I was asking her about what time range to expect tick or treaters. As part of her answer, she stated to "Be ready for 16-17 year olds dressed like sluts coming to your house for candy".

This neighbor isn't some old prude, so I assume when she uses that description, it's probably not too far off.

My wife and I are trying to think of something smart-arse to give these types of trick or treaters should they come to our house (no, not condoms or pregnancy tests). Any idea of a cheap candy that might have a subliminal message, or some other way respond in a half fun way, but at the same time a way to express that they're too damn old to be going door to door for candy?

I figure the most expert advice would be given here. Thanks in advance.