In this episode, Philip and Vivian go away on a trip and leave Will and Carlton home alone. While they are away, Geoffrey (the butler) has a date with a woman he met through a dating service. Will and Carlton decide to throw a small get-together at the house, which predictably spirals out of control into a massive house party. Wifiman Testflight [FAST]
Here is the information for : Episode Title: The Butler Did It Original Air Date: February 11, 1991 I Saw The Devil Download Torrent Hot
It is highly likely you are referring to (often typed as "1x18" or "118" in shorthand).
Meanwhile, Geoffrey's date turns out to be a woman who has ulterior motives, leading to a comedic situation where Will and Carlton have to help Geoffrey while simultaneously trying to hide the evidence of the party before the parents return.