I don't understand why it is funny. Why is the fact that Hiddlestoners get Hiddlestoners funny?
Native speaker’s answer
Rebecca
"Hiddlestoners get Hiddleboners" is a bit of a lewd joke. It is a wordplay on the Hiddlestone brothers' last name. "Stoner" from Hiddlestoner means a habitual user of marijuana, and "boner" from "Hiddleboner" means an erection.