Jordache Jeans
In the episode "Life of the Party", Daphne tries to encourage Marty to dress younger. He replies, "Nah, I tried those Jordache jeans. I just think you oughta leave somethin' to the imagination."
For a long time, I thought he was mis-pronouncing Jordache like he does when he says "Avanti Tux" (instead of Armani). I've just looked it up and apparently Jordache jeans were a popular designer brand in the 70s and 80s. Wiki also notes, "In the 90s, Jordache products slid in popularity. The company's jeans lost their cachet...typically selling at discount stores."
Is this common knowledge in America (I'm from the UK)? I think it's genius - Marty tries to dress youthfully and goes looking for 70s/80s fashion. The idea of finding these clothes in a discount store is also classic Marty (like the crease-proof shark skin suit he bought that was rolled up inside a mayonnaise jar)!