The Rembrandts are a power-pop duo who have been around since 1989 and who became briefly famous in the mid-’90s, when their song “I’ll Be There For You” became the theme song of the TV show Friends. Obviously, Friends stayed huge, but the popularity of “I’ll Be There For You” was such that people wanted to hear it even when they weren’t watching Friends. The song was in heavy rotation on alt-rock radio and everything. It was weird. Anyway, Friends turns 20 on Monday, and someone marked the occasion by putting up a pop-up version of Central Perk, the show’s fictional coffee shop, in New York. The Rembrandts played at the pop-up, doing “I’ll Be There For You” acoustic for a crowd that couldn’t figure out that they were supposed to clap during the clapping part. They also played Phoebe’s perennial open-mic song “Smelly Cat” and then played “I’ll Be There For You” again, this time with the guy who played Gunther (James Michael Tyler) helping out. Buzzfeed has video of the theme song performance, but there were no umbrellas. Go watch it and feel old. “Smelly Cat” looked and sounded like this: