What Makes Up the Name: boredom + orgasm
So that was weak. Look, it's a long list. What can I say? Now is a good time for your boregasm, when you're so bored that the boredom climaxes and washes over you and you look over and you realize you never even really liked this list, or portmanteaus and you sneak out the back door and you never call us again.
Origin: There's blog entitled Boregasm going back to 2006 and the Urban Dictionary has it entered in 2009, so probably somewehre in the aughts.