We call him lobster legs because his legs are golden as if they've been dipped in butter.
Also because whenever he wears mesh stockings his leg hairs get caught, giving him a nasty pinch which causes his legs to gyrate like they were lobsters struggling in a net.
Also because sometimes he breaks out into song about how it's much better down where it's wetter, if you catch my meaning
Also because whenever he is placed in boiling water he makes a shrieking sound theorized to be steam escaping his hard outer shell since Grislyguses are well known for not having any feelings.
Happy birthday grisly