(Strip Number 1419, Original Publication Date, 14 February 1989)
Panel 1: Having been asked if he can sit for the Richards children, Mike guesses that he can babysit Christopher and Richard for an hour or so. You will notice a name that is absent from his list of people he can coexist with. This becomes important.
Panel 2: As she resumes her phone call, Elly tells Anne that he'd love to sit for them. Upon being told that they're heading out for seven in the evening, she says that if the boys are in their pajamas, he'll have no problem at all.
Panel 3: She stretches credibility past the limit when she cheerfully declares that he can change baby Leah's diaper if he has to. His response is to repeat the word 'BABY?' as he does the goggle-eyed teeth-of-evil muppet-mouthed freakout.
Panel 4: Since he's stupid, he asks "They're leaving the BABY?" because he's dumb enough to think that Steve and Anne want to take a colicky two year old along to a romantic evening out to make his life easier.
Summary: Next Wednesday, he howls WAN'MAMMA!!!!! because the idea of changing a diaper (and thus exposing himself to an unknown level of teasing from the assholes he mistakenly thinks are his friends) terrifies him beyond mortal comprehension and is also too much to ask of him. Twenty years from now, he howls Deanna's name because the idea of interacting with the strange half-humans who have a baffling and wrong curiosity about his life terrifies him beyond mortal comprehension and is also too much to ask of him.