High geek speak for entering and closing any rant on any topic. Using html coding conventions in discussion usually in instant messages, text messages, or other written communications.
Me: That was fine but what i'm pissed about is <rant> they didn't invite me to their party.
You: OMG you've opened your rant tag. here goes...
Me: Believe it! those guys are jerks! Ok. I got that out of my system</rant>