There's a rule in the movie "Wedding Crashers" where you're only supposed to draw attention to yourself in a POSITIVE way.  So, not this . . .

A 37-year-old guy in Florida named Mark Saunderson crashed a wedding at the Grand Plaza Hotel in St. Petersburg on Monday.

Apparently he'd already been drinking.  Then he strolled into the reception and hit the open bar, even though he didn't know the bride or groom.

But he ended up drawing the wrong kind of attention to himself when he stumbled onto the dance floor . . . and tried to cut in on the bride and groom's FIRST DANCE.

He took off when security showed up.  Then they chased him up to the roof, where they held him until cops got there.

According to police, his eyes were bloodshot and he was slurring his words.  And when they asked for his social security number, he gave them his phone number instead.  He's facing charges for disorderly conduct.

The couple says they WEREN'T actually upset though.  They thought it was insane . . . but in a good way . . . and hope Mark had fun for the short time he was there.  

(WFTS)  (Here's his mugshot, along with photos of him dancing and the couple reacting.)