A one-dollar bill. This term is usually used when bribing somebody.
Girl: "I told you, I'm not gonna let you beat it up. You have herpegonnosyphiltitis."
Boy: "Well...that's not what Mr. Washington here says..." (pulls out a crisp $1 bill and offers it to her)
Girl: ***SMACK!!!*** "Fuck you nigga, my mama didn't raise no ho!"