しもネタは禁止だよ～。

lower reaches (of a river); bottom; lower part; lower half (of the body, esp. the privates); feces (faeces); urine; menses; end; far from the imperial palace (i.e. far from Kyoto, esp. of western Japan); dirty (e.g. dirty jokes, etc.)

material; joke material; contents; proof; topping of nigiri sushi

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

prohibition; inhibition; ban

be; is; indicates past or completed action; indicates light imperative

indicates certainty, emphasis, contempt, request, etc.; used when calling out to someone; used to catch one's breath or get someone's attention; yo!