There are specific, extra-long songs called "toilet tracks" that we play if we need to shit.
Back in the day, it used to be the nine-minute album version of "Free Bird" by Lynyrd Skynyrd. These days, it's more likely to be a bit of long, indulgent '90s indie, like the Stone Roses' "I Am the Resurrection" (8:13), or "Fools Gold" (9:53).