The joke is that the meme has bad grammar, deer is plural. Rather than point out the obvious, I say that ant is plural, which is funny because it is both stupid, and draws attention to the deer/s. When my comment wooshes over heads, I follow it up with an even stupider comment, thinking that nobody could possibly be stupid enough to think that there is someone out there that thinks ant is a plural american english version of the British ‘ants’… and then I am once again astonished.