Those who were old enough to live through the peak-MTV era probably remember Dave Grohl randomly shouting "Axl! Axl! Where's Axl? Hi, Axl!" after Nirvana's "Lithium" performance at the 1992 VMAs. The odd moment (which included Krist Novoselic's bass smacking him in the face) wasn't explained until a few years ago.
In Krist's 2008 Seattle Weekly article, he revealed that an annoyed Axl Rose told Kurt Cobain and Courtney Love "Keep your woman in line," after Court exclaimed he was their baby's godfather. The backstage incident led to Nirvana trolling MTV by playing a few chords of "Rape Me" prior to "Lithium," and Grohl's aggressive shout-out to the Guns N' Roses frontman. So what's the lesson here? Don't mess with a rock star's wife.