Billy then replied, "Sean, stop being such a Coupon."
"Yeah man, whats with your Coupon Methods these days?" Brian asked.
By constant use the term 'coupon' itself comes to mean the thing for which it is a token, namely, oral sex.
Believed to be derived jointly from the prevalence of coupons in late post-industrial/capitalist society (largely exchangeable for low-quality goos - see coupoff) and from the Scots/Irish/Gaelic 'coupon' meaning face - coupon/face then suggesting head or oral.
D'you fancy a coupon when we get home?
Some people even associate this coupon with the act of pregaming. Pretty much anything dranken while pregaming to any event could be considered a coupon.
Person 2: It's cool dawg I brought my coupon, ill take it and leave it in the trunk, drink from that before we go in and all night while we thurr and youll be able to spend all twenty five dollars on some hoes!
It's not uncommon to find certain catches, i.e. "FREE! With the purchase of 20 identical items."
Usually affiliated with being dirt poor.