Thank You Scientist are seriously talented musicians who make very complex music, but don’t take themselves seriously and have fun with their performances.
How silly are you looking for? It doesn’t get sillier than We Ran Out Of CD Space by PsychoStick… or anything else by psychostick. But there’s also Ninja Sex Party, Wolves of Glendale, First of October (listen to Ravioli).
While not outright comedy, there’s a humor to Falling for Me by Parker the Bandit and It’s Okay to Punch Nazis by Cheap Perfume
TENACIOUS D! I unironically listen to their first album a lot lol. Weird Al, obviously. Suburban Lawns, the Aquabats, Reel Big Fish, Green Day (the album Dookie in particular), Presidents of the United States of America, Primus, Mr. Bungle, the Adicts, the King Kahn & BBQ Show, Nobunny, Weedeater, Spazz, Gravy Train!!!, the Pixies, GWAR, King Diamond, Busdriver, MF Doom, Talking Heads
Your mileage may vary with some of these; some don’t mean to have a funny shtick but I just find them funny personally