Flagpole Sitta by Harvey Danger. It feels good to be back in 1998.
edit: @SML looking at their wiki it looks like Nada Surf opened for them one time. You were, coincidentally, the person who discovered to me Nada Surf with Popular.
Nearly 20 years later I still feel lucky I was able to make the trek to see BTBAM perform the entirety of Colors live. Still have the tour shirt somewhere too.