An Affair to Forget

S2, E19: When Ellen (guest star Leigh-Allyn Baker) and Rob (guest star Tom Gallop) announce that they are getting married, Grace (Debra Messing) feels forced to reveal to Will (Eric McCormack) that she once slept with Rob - a secret that surfaces at Ellen's bachelorette party, and prompts Ellen to seek revenge. During Rob's bachelor party, Jack (Sean Hayes) is confused and baffled by his reactions to the entertainment. Megan Mullally also stars.