Word of the week: sỉn
(Say) sỉn is an adjective or verb expessing being drunk, intoxicated, or just plain hammered. For example, "Tôi say sỉn" means "I am drunk". "Say sỉn" may be more formally correct, but Vietnamese often elide it down to "sỉn" in spoken speech. Thus, "Tôi sỉn" also means "I am drunk", and has the added advantage of being shorter. When you're pissed, terseness is indeed an advantage.
Today's the first day of Tết, and there's a lot of sỉnning going on right now.
UPDATE: After some discussion with my wife, I learnt that the word is not "sỉn", but "xỉn". (That is also what "Anonymous" claimed in the comments section). My apologies.