Zac Efron One Man, DOUBLE the Fat Tip

6/7/2011 4:00 AM PDT

Zac Efron -- One Man, DOUBLE the Fat Tip

Zac Efron threw around cash like a BALLER at a San Diego hotel last Friday -- dropping $700 in booze and then leaving a 40% tip.

Efron hit the Float Bar at the Hard Rock Hotel with a group of friends ... and ordered up one bottle of Kettle One vodka ($350), one bottle of Patron Silver ($350) and a 6-pack of Red Bull ($30).

Sources at the hotel tell TMZ, Efron covered the $140 service charge on his bill ... then dropped an additional $150 just for the hell of it. Grand total -- $1,093.50.

In total ... that's about a 40% handout -- and we're told Zac played it cool the whole time he was there.

Must have been all the Red Bull vodkas.