It’s the percussive slap in funk. Cows don’t have a lot of funk... you don’t hear, “Get the Mooos out!” Funky people like super-fly and burning down the house. Cows don’t like flies of any sort and having their barns burnt down. And they don’t like Flea as a bass player cause the tattoos makes them think of branding and the name Flea bring back memories of nests of fleas in their ear. So that about explains it. The pop and slap are annoying too but I won’t explain just yet.
I wonder how the herd would have reacted if the bassist were Charles Mingus and the amp was a Polytone or one of those AMPEG Porta-Flex Flip-Flops with the 15”. I know I would have stuck around.