From Rocklopedia Fakebandica
Wapsi Square (2001). The band- Jacqueline Bontemps (drums), Owen Albrecht (guitars/keyboards), Shelly Wahnee (bass)- took their name from an incident early in the strip, when another character (Monica) attempted to brush her teeth in the dark. Instead of toothpaste, she squeezed the contents of a fermented banana onto her toothbrush. Yeah, we're not buying the whole concept of a person keeping a fermented banana next to the sink either. Name origin strips here and here.