Les Claypool, that cartoonish-sounding singer and slap-happy bassist you hear in the opening credits of “South Park,” has been kicking out the jams for 27 years with his combustible trio, Primus. Touring behind new EP, “The Desaturating Seven,” based on an Italian children’s book about goblins who devour rainbows, this is the first time the original trio featuring guitarist Larry LaLonde and drummer Tim Alexander has reunited for a record since 1995. Delightfully weird and musically precise, Primus plays the National on Wednesday, Oct. 25. 8 p.m. $36.50. thenationalva.com.