Senators Jeff Flake and Cory Booker Snowball Fight on Capitol Hill

Donald Trump and Joe Biden's hypothetical high school brawl apparently has D.C. in a fighting mood -- 'cause 2 senators actually got into it ... with snowballs.

Republican Sen. Jeff Flake and Democrat Sen. Cory Booker had themselves a good ol' fashioned D.C. duel early Thursday morning outside the Capitol.

Flake was clearly poking fun at Trump and Biden's beef. As he put it, "With so many fights on Capitol Hill, @CoryBooker and I are going literal: Snowball duel." The stakes ... loser buys the other's staff pizza.

Booker accepted the challenge, and predicted a win since he's from New Jersey, and Flake's home state of Arizona "doesn't have much snow." He probably shouldn't have been so confident, though ... he later said he lost the duel, and would be shelling out for pies.

Unlike Trump and Biden -- who apparently wanna beat the actual living crap out of each other -- Flake and Booker seem to actually get along from opposite sides of the aisle.