One of the first “dirty” jokes I heard when I was 10

So Jane sees Tarzan sneaking off one night and goes investigating. She follows his trail and finds him furiously humping a tree-trunk that has a curiously well-used looking hole in it. Initially disgusted, she’s mollified thinking, “At least he wasn’t doing it with other animals like everybody else claimed, this was his best way to relieve stress for all those years.” At that, she decides Tarzan need not go through that ordeal ever again.

The next night, she sits next to the door, all dolled up and inviting, legs spread wide open, waiting for Tarzan. When he finally makes his appearance, he sees her and makes an enquiring hoot to which she replies, “I know where you’re headed off to, you don’t need to suffer through that indignity anymore now that I’m here”, while gesturing to herself.

Tarzan looks her up and down considering, then nods his head, comes running at a full sprint and kicks her right in the puss. Jane, now rolling around in agony, anticipation all forgotten, asks him with tears in her eyes, “…why?”

Tarzan shrugs, “Checking for squirrels.”