S.I.M.P Share definition Flag An acronym for the song "Squirel in my pants" from the famous children's show "Phineas and Ferb". Friend:Did you hear the new song S.I.M.P S.I.M.P by BateMilko April 17, 2020 0 0 Get merch Get the S.I.M.P mug. Buy Now — $32.95 See more merch