What was Seagal painting on the tips of the bullets he was putting together for his silenced sniper rifle prior to going to Jamaica to assassinate Screwface. I'm guessing he is painting them with Teflon which might defeat a bullet proof vest.
He's writing "you bin whacked by segal biotch!" in extremely small letters. Of course the man getting shot would not know this as segal is the only one in on the joke.
Actually, the little vial he's dipping the stuff out of, has a chemical formula on it, that you can just barely make out as the scene flashes by. I'm thinking it's one of two things; either Mercury (and I'm doing this from memory - I've only seen it about a bazillion times - but I THOUGHT the compound formula on the bottle contained the letters, "Hg"), so as to REALLY finish you off, if the bullet doesn't hit a VITAL area (a not unheard of practice amongst professional snipers & black ops sorts), OR, it's a C4 compound, which would make the bullets, an explosive-tip variety. Either way, Seagal - as ALWAYS - plays for KEEPS! :-D
If you pause the film you can clearly see that it is a bottle of Mercury (heck, it says "Mercury" at the top and Hg underneath it). I think that filly a bullet tip with Mercury would have a negligible effect, if any.