If my next birthday doesn't involve a gift on the same level as Jennifer Garner playing the saxophone for Reese Witherspoon, I'm going to be a little upset. Jennifer threw it back to her high school days and put on a fully decked-out marching band outfit to play a song for her longtime pal in honour of her 43rd birthday on March 22. "Many moons ago, my high school marching band played this song for homecoming. Today I play it for my boo, @reesewitherspoon," Jennifer captioned the hilarious video. "We have a groovy kind of love," she added, referring to The Mindbenders' hit "A Groovy Kind of Love." Between the big hat, Jennifer's unwavering concentration (the page flip!), and the fact that she's just casually in a backyard filming this, it's truly iconic friendship behaviour. Consider this another reason Jen's Instagram is the best.