Short for "supplement", usually referring to the act of combining different flavors of smokeless tobacco in one's mouth. This most often occurs when one person has reached the end of his/her can, but feels that the final dip
is too small. He/she will then ask a friend for a suppy in order to bring the dip to a respectable size.
Me - Shit, I'm all out of straight. This dip is weak. I need a suppy.
Wife - Here you go, luv, have some of my mint.