cap

Cap, usually means the opening to a bottle that you can screw on and off. Cap also can mean a hat with a sturdy flap on it. But cap can ALSO mean something that is not true.

hey, gimme that bottle cap. My water bottle is gonna ruin all my stuff if it sits open like that.
Yo man, that's a cool cap you got there! Where'd you get it?
Huh. That sounds pretty cap to me. I highly doubt this will work.