gas station game

i've begun playing a game with the gas station attendents i see at least twice a day. first, i go and buy a pack of cigarettes at gas station number 1. later, i go buy a Mega-Buddy (a 64 oz. fountain drink) at gas station number 2. sometimes, i get gass, but that's not everyday and that's at gas station number 3. when i need air in my tires, i go to gas station number 4. that's my long explanation telling that i go to lots of gas stations. here's the game: after i purchase whatever i presently desire, i immediately say "have a nice night" or "have a good day" because they're supposed to tell me that. about 20% of the time they panic and don't know what to say. about 10% of the time they smile, thank me, and wish me the same. the other 70% of the time they ignore the fact that i was polite and just wish me a good night while not looking. it's a fun game.