This television episode refers to:
September 12, 1981 - January 12, 1990
After the group suffers through Lily's play, everyone (except Barney) tells Lily how much they enjoyed the play. Barney is honest and tells her it sucked. Lily is upset, saying friends are supposed to be supportive and encouraging and life each other up. Barney remarks that those ideas are fine, if you're a Smurf.