A period lasting at least an hour of listening to awesome music by the most fantastic band ever made (MUSE) whilst reading and looking at anything associated with them.
Guy: 'Duuude why were you liking so many MUSE groups on facebook? And continually saying how underrated 'Sing for Absolution' was?'
Girl: 'Sorry man, I went on a bit of a Muse-athon - but hey, at least it's not some sucky twelve year old girl' (see Justin Bieber)
The name for an often public and ostentatious display of affection. Typically of the offensive and unappealing variety, an Get-it-on-athon is something to the liking of an NC-17 movie acted out in real life, for prolonged periods of time in a fairly public setting.
"Ugh, did you see those people in the front of the movie theater having a Get-it-on-athon in front of everyone? so disgusting," said Kaiti.
"Yeah, honestly that's when you need to leave 8 dollar movie and check into a thirty five dollar hotel. So nasty." said Hannah.