Quite a lot of dolphins in the Stregaverse can open their jaws wide enough to swallow a whole human. A fair number are flexible enough to swallow even a dolphin their own size. (A drawback of being perfectly streamlined is being also perfectly shaped to be swallowed easily.) The tail may hang out for a while, but only until digestion makes room further down.

The lesson to be learned by horny male dolphins is don't be too insistent about wanting to "Spend the night inside someone". Push too hard and he may well find more than his penis inside his would-be lover.