Shaq Rejected Charlie Sheen ... Refused Epic Party Invite!

Shaquille O'Neal's no idiot ... and SMARTLY turned down an epic invitation to party with Charlie Sheen and rock legend Matt Sorum back in the '90s ... 'cause he thought he would die.

It's a pretty hilarious story ... Sorum, who drummed for Guns N' Roses, Velvet Revolver and more, says it all went down back when Shaq was playing for the Orlando Magic.

Sorum says Shaq couldn't have been nicer when they asked Shaq to party with 'em -- but explained why he had to respectfully decline.

"I really felt he was concerned he wouldn't return from the excursion unscathed."