Arsenio Hall -- Crowdfunding to Buy Clippers ... Gets $1,100 from Katt Williams

Arsenio Hall says he's trying to raise $1 BILLION to buy the L.A. Clippers ... and last night he got his first REAL donation ... a wad of cash from Katt Williams.

While Arsenio's campaign might be a joke, the wad of cash Katt gave to Arsenio was not -- sources tell us he gave Hall $1,100 in $100 bills ... and did NOT ask for it back when the cameras turned off.