Having sex in a box. Most commenly when a man or woman is homless and living in a box and a someone sees them and they end up making love in his/her box.
"That homless guy is really sexy, I'm going to go have boxsex with him"
"That guy totally just had boxsex with that girl"
"That guy totally just had boxsex with that girl"
by Holly Heaton February 18, 2010