When you decide to have sex with your lover, who is unfortunately (for both) menstruating. Also, she has been plugged with a tampon, strings all a'danglin'. During intercourse, the tampon appears to slide out, much like the horn of a unicorn.
A potentially sedate weekend in Daylesford may have been caused by an awkward round of "Fucking the Unicorn"...
by Not High Enough In A Hammock August 18, 2012