Chandler accidentally sees Rachel's breasts, setting off a chain of boobie payback events. It provided some good comedy, some funny mix-ups and some clever lines.
My favorite storyline of this episode though was Joey finding out about his father's affair and playing parent. It was really funny, there were some great lines and it let us get to know Joey a bit better.
The episode is filled with funny lines, great comic timing and some great chemistry between the actors, both regulars and guest stars.