Well, this isn't current but Grover and the Everything in the Whole Wide World museum has very slapstick humor. (And cracks my 4-year-old up, even after we've read it 100+ times.) BUNNIES by Kevan Atteberry also cracked him up, but I'm not sure it qualifies as slapstick. I think of slapstick as involving gags like running into walls or falling down stairs for humor--is that what you're thinking? In BUNNIES a kind monster who desperately loves bunnies keeps spotting them and chasing them and they get away. (My description doesn't do it justice--it's really cute!) The Piggy & Gerald book I BROKE MY TRUNK seems like slapstick humor to me, also PIGS MAKE ME SNEEZE. SAMANTHA ON A ROLL by Linda Ashman has kind of an absurdist slapstick humor. DINOSAUR KISSES by David Ezra Stein might be another good one. Or STUCK by Oliver Jeffers, although that one might be more absurd humor than slapstick (but I think it's so funny!)