[quote me] tips are given, not asked for.

have you ever been asked for a tip?

at best, service-workers, like bellboys for example, could stand and wait in front of your room but i don't think can they ever verbally (or by hand gesturing) ask for a tip.

it's not just tip actually.  there are others out there that are given, but never asked for.  what else can you think of that are like that?