When I was a kid, I thought I invented the word summersault for a tumble. But it seems so unconnected to what the word means that surely I’d heard it before, and it wasn’t synchronicity.
Metroflexual - someone whose orientation is…ambiguous…
…in theory.
A runcible spoon. Duh. 
Not mine, but recently from the mouth of my love:
Snuffligate - The very intense investigation dogs perform with their noses.
“Man, Marley and Jack just had to snuffligate my shoes when I got home.”
Snuffligation, Snuffligating, etc.
Damn! Beat me to it!
It’s not technically a portmanteau, but I have one friend who is NOT an optimist by any stretch of the imagination. I call him a mope fiend.
Twittiocy - The use of Twitter to broadcast one’s idiocy
Thought of two more by the same man…
Vajaycancy - What you have if you’re a single woman.
Mirth Quake - The shaking one does when trying to stifle a laugh, as in church or a staff meeting.
A friend of mine and I came up with Affucktion to describe our relationship.
Think FWB but no intention of going further.
We need a word to describe a certain kind of celebrity.
Not someone who became famous for being a good actor or singer, but acquired fame through no discernable talent…like Snooki or the Kardashians. 
Shrugnostic: a person who doesn’t care whether god exists.
**Thurtening **: Actually a friend of mine blurted out, “It’s thurtening!”, hearing thunder and seeing lightening at the same time when we weren’t quite realistic under influence, a long time ago. That cracked up some 30 of us for at least over an hour well after midnight and the local cops came to the camping ground to shut us up to no avail.
Celebrinobody ??
Shagnostic a person who doesn’t know if their lover is really seeing God or if they’re just faking it.
Fake boobs? Foobs. “Bolt-ons” is also acceptable.
Whaaaaa? Are you sure that isn’t a still pic from an SNL skit?
::golf clap::
My sister and I came up with “riffkiss”. It’s how we pronounce “RFQS” which stands for “Reduced for quick sale”. Derived from the stickers the grocery store puts on cut fruit, fresh meat, and dairy products that are about to go out of code.
I came up with “hextuple-u”. Example: “hextuple-u straightdope dot com”. Two u’s times three = six. Ergo, hextuple-u. For some reason, it hasn’t caught on. 