It's fairly stupid but it does involve him thinking like a regular six year old.
Panel 1: As they walk from the bus stop to the Pattermanse, Mike declares that girls are weird; Lawrence counters that maybe not all girls are but Mike is insistent on the point. Reason: Deanna wouldn't respond to his acting like a stalker with a crush.
Panel 2: Mike's silhouette says "I should know; I've got a sister." Lawrence's silhouette asks "What about mothers?"
Panel 3: As Lizzie's silhouette looks on in the background, Elly unhinges her jaw and yells because Mike forgot to put his shoes in the boot tray again and has thus walked off the tiny mat she put on the big, bare floor.
Panel 4: As they sit in his room, Lawrence tells Mike "You're right; girls are weird." The reason he does so is that Elly screamed about the dirt on the carpet and not Mike's tiny little feet.
Summary: When you consider that Mike's 'expertise' about women comes from exposure to the freaks that inhabit the Patterverse, you remind yourself that neither he nor Lawrence can hardly claim to be a guru of any sort.