(Strip Number 899, Original Publication Date, 25 July 1985)
Panel 1: We find Mike under a table telling Lawrence that the secret to staying up at a grown-up party is to not let the adults know you're around.
Panel 2: Having noticed that he stole a bottle of cherries, Lizzie offers to report that fact by yelling MAAAAAAAAAA!!!!!!!!
Panel 3: This causes Elly to notice that yes, the kids are still up.
Panel 4: As Rage-Face Elly marches them off to bed, Mike thought-bubbles that the real secret is to gag your kid sister.
Summary: While I do support the not-staying-up-past-bedtime part, the whole "rage" thing seems to bother me. That's because I'm more inclined to worry about small children becoming overtired than I am about chaos-loving monsters learning something they can blackmail Mommy with.