Verb
seal the deal (third-person singular simple present seals the deal, present participle sealing the deal, simple past and past participle sealed the deal)
(idiomatic) To come to an agreement; to finalise the deal.
Okay, here's a tip: if you're doing something creepy like molesting children, you don't need to take topless photos of yourself to seal the deal. We know, the pedosmile is enough. Maddox