'All That' Reunion Has No New Material ... For Now

"All That" fans might've prematurely slimed themselves over Nickelodeon's reunion announcement -- TMZ has learned the special isn't what it seems.

Nick sources tell us the reunion won't have any new sketches -- no Repairman, no Vital Information, nada -- instead it'll be reruns of Nick's classic '90s shows with commentary in between from cast members Kenan Thompson, Kel Mitchell, Danny Tamberelli, Lori Beth Denberg and Josh Server.

But there's still hope for a REAL reunion -- with new sketches -- according to Tamberelli.

The chances are solid since Thompson, Tamberelli and Server all still do sketch comedy -- sometimes together -- and Danny believes they'd be down if their schedules allowed it. Mitchell's back on Nick with a new show.

Denberg -- the only non-performing cast member -- is a wedding officiant. But Tamberelli says if she or anyone is on the fence, he'll press them hard to get on board.

All they need now is a green light from Nickelodeon.