DeMario Jackson and a bunch of other 'Bachelor' alums apparently love it doggy style ... when it comes to charity auctions.
Five former 'Bachelor' contestants threw on their fanciest garb Thursday night and stripped, sung and danced at the "Cocktails for Canines" fundraiser benefiting the Tri-County Humane Society in Florida.
Vinny Ventiera hosted the shindig with his pals Josh Murray, Daniel Maguire, Ryan Beckett and DeMario ... all of whom helped raise $10k. 'Bachelorette' star Luke Pell also put on a striptease show last year.
The winning bids got dinner and a night out on the town with their man.
No word if a Fantasy Suite was included.