Family Matters - Season 5 Episode 24 -

Urkel decides to renovate his Stefan Urquelle alter-ego, inventing a transformation chamber to do the trick. Stefan is much more likable this time, but just like the last time, the formula soon wears off and the suave ladies man is soon his old irksome, nerdy self. Urkel declares that he will find a way to make Stefan permanent ... and win Laura's heart once and for all.