It's Punky Brewster S01 E05 Punky Wise and Pound Foolish / A Small Mistake

Punky talks Margaux into attending dweeb Avery Bigelow's dad's party so she can win a photo job for Henry. In primping Margaux up, Glomer prepares a facial that turns Margaux's face into a glomley face. Punky has to disguise herself as Margaux until the facial wears off.