A song originally by Shel Silverstein, popularized by Johnny Cash. The song is about a man on death row on the day of his execution counting down the time to his demise minute by minute, from his last meal until the hanging.
Despite being very dark, the song is considered quite humorous due to Johnny Cash's hilariously animated music video to accommodate the fact that he would die if he tried to re-enact the execution.
Despite a blatant error near the end where he says "Seven more minutes to go," instead of "Four more minutes to go" (which was later corrected in the live version), the song was very well received. Johnny Cash's darkest songs tended to be his most amusing ones as well, after all.
Well, they're building a gallows outside my cell...and I've got 25 minutes to go
And the whole town's waiting just to hear me yell...I've got 24 minutes to go