Jimmy Kimmel is doing some major trolling of Spencer Pratt after Spencer lost the Los Angeles mayoral race ... renting a U-Haul for the former reality star to drive him out of town for good! Jimmy did his Spencer-bashing routine during the opening monologue of his Tuesday late-night show -- and the host didn't pull a single punch. Check out the video ... Jimmy starts off by bringing up that Spencer promised to move out of L.A. if he lost to incumbent mayor Karen Bass and city council member