When promptness bites you on the butt

My big question about today's strip is, Why do Barfo and Lula look so surprised to be getting a dinner invitation? Perhaps the amazement is that they actually received it in the mail. Do people send invitations through the mail anymore? I mean, maybe for, say, weddings and baby or bridal showers. In any case, the open-mouthed shock of Barfo is a bit over-the-top. And looking at the invite, perhaps the problem is that the Crovneys don't actually put a date on the invitation. Are the guests supposed to guess?

But no, this has never happened to me. Sure, I've gotten to places where the host is still putting the finishing touches on things, but never have I arrived to find the hostess in a robe and curlers. Obviously these people are insanely rude--telling the husband to shut the door, presumably in Barfo and Lula's faces? Also, Alf is wearing a pink undershirt under a white shirt. Does this make sense to anyone?

At least Barfo and Lula look happy in the bottom panel. (Really, what's up with the "We'll be there on time!" in the top panel? Who says that?)

I think we'll have to draw straws to break it to Al that Alf is actually the name of an alien from Melmak.