Probably.
Even been to a touch pool at an aquarium? The anemonies on display are very tame. Their stingers have a sticky, lightly sandpaper-like texture to them and their toxins are very, very, very, mild. Doesn't hurt at all. They react to touch by pulling their tentacles into their mouths and closing up.
Imagine sticking your dick into one of these and feeling all those tiny little stingers as they grip onto you around the base of your cock. The smooth actinopharynx caressing your sensitive flesh as its sphincter muscles close up around your member. As you gently pull out, it holds you in place. As you cum, your sperm is united with their gametogenic, reproductive tissue and your seed mingles with the hermaphroditic creature's sperm and eggs.
Too bad the ones that are big enough to accommodate probably sting like hell. They prey on larger creatures, so their toxins are more potent to quickly paralyze/kill their prey to prevent them from thrashing about and cause damage during ingestion whereas the smaller ones get their nutrients from microscopic plants and creatures floating around in the water.