I have a 2003 Harley Davidson Fatboy, bought it used in 2006. First thing I did was change the oil. The oil dipstick is a dagger. I thought HD just put it in there to make it outlaw-ish. Took the bike to the shop the other day and the owner looked my bike over and said "you're not from around here are you?". I told him I'd lived here for around three years and asked why he would say that. He told me the dagger oil cap was illegal in CA and I could be arrested on a felony charge for carrying a concealed weapon. Sort of freaked me out. I'll probably change it out for a normal oil cap.
It looks something like this.