Sevvy was what Sirius would call Severus in his head if the man would ever lighten up. Sure, they were horrible to one another when they were kids (okay, so Sirius was horrible to Severus when they were kids, but who's counting these days) but now they could at least attempt civility. If only Severus would lighten up - and anyway, Remus was always saying Sirius should play well with others...
He pushed back his next shot, his grin growing slightly more lazy due to liquor swiveling around his system. "Troublesome, my dear Sevvy, is the understatement! Could you imagine!" Next, because regardless of alcoholic consumption or not, Sirius acted like a fool in public - so he started to wave his finger around as though it were his wand, but instead of saying spells, mumbling things like "pue, pue, pue!" like the lasers from muggle laser-guns (so to speak.)
Sirius reached out for the next shot of his (that magically appeared, he'd have to remember to tip Jim bigger than usual), then clapped Severus on the shoulder. "My foot is a lovely specimen of foot...hood. Care to see?" Sirius nearly brought his foot up for Severus to inspect, but thought better and kept them firmly planted to the pegs on his stool.
Yes, the world must be ending. Sirius Black and Severus Snape were almost having fun together. And aha! Severus was a vampire! Oh, the thinks that Sirius could think.
"I have a suspicion that a firewhiskey-flavored Sirius would be most appealing, to many a persons. I think you're exaggerating dear boy." He leaned in further to ensure that he wasn't actually dueling with a vampire (you could never truly know with Severus) and then pulled away again, taking down his shot. "And if you are trying to lure me, you're doing a bang up job of botching it up."