As the audience cheered, the actresses gave a rendition of Phoebe's self-composed song Smelly Cat. And hitting the right notes wasn't really a concern if they wanted the performance to reflect Lisa's character's dubious musical talents in the series.
The track – which first appeared in season two, 1995 - is undergoing something of a revival. A dance version of the song is currently doing the rounds on the web.
When told of the new development with the song, 46-year-old Lisa said: "I can't wait to hear if it is any good," noting the original "is a good tune".
The blonde star and her pal Courteney joined a bill of established performers in taking part in the Rock A Little, Feed A Lot concert, which raised funds for US hunger-relief charities.
Others taking part included Alanis Morisette, Sheryl Crow and Ben Harper.