Speaking to reporters following Chicago's 4-3 loss Tuesday afternoon, Morrow explained that he experienced back spasms "taking my pants off" at "like 3 a.m." on Monday after the Cubs returned to the Windy City following a three-game set with the St. Louis Cardinals, according to The Athletic's Patrick Mooney.
"It's frustrating any time you can't get out there, and especially when you can't go because of something stupid like taking your pants off," he added.
Morrow isn't the first Cubs player to hurt his back in strange fashion.
Fourteen years ago, slugger Sammy Sosa suffered a sprained ligament in his back following a couple of big sneezes and landed on the disabled list.
Morrow will hope to avoid the same fate.