[AutumnCurtain]

A spiff is a free giveaway attached to a sale, historically a bonus for salespeople for making the sale but colloquially also for customers getting a freebie item with a purchase.

[reaperducer]

Also used to describe anything given away for free by salesfolk hoping to land a sale.

Think of the big bags of crap that used to be given away at CES, or when a Microsoft rep would show up in the office and hand everyone new mouse pads.

[QuercusMax]

I always thought that was swag...

[hw-guy]

I always thought it was a joint (what the New York Times calls a marijuana cigarette).

[QuercusMax]

you're thinking of a spliff (note the L)