So this is Admiral Ackbar, whose line is ITS A TRAP!

He looks kind of like the pursehead.

Then there is "Trap" a colloquial term for a male who is disguised as a woman such that other males can't tell them apart.

It would be funny if Ackbar said "ITS A TRAP" in reference to the Pursehead character who would then snap back about no longer having any male genitalia, such as a post-op transgender.

This humour is highly subjective and you may not find it funny even after the explanation, but I see the head shape and faux fur coat and immediately imagine a confident, sassy, deep voiced woman who mocks Ackbar's interpretation of her gender.