Secret Achievements:

Potty Trained: Peered curiously into 150 toilets looking for phat lewts.
Sir I Can't Help Myself: Steal anything not tied down until the Entire FNV Universe Hates You and you CTD in a hard digital vaccuum. (your Internet Connection makes a sound like hammer-lock in response.) {And if you're in any doubt? Yes, it is all your fault!}
The Inferiority Complex: Due to your Development Speed (& some Lever-Action Bugs--) you find yourself developing your Companion easier then develoiping yourself. They are now much more hardcoe than you. Also known as the 'I'm on Point' or the 'At the Rear of the Advance I can be at the Forefront of the Retreat' (Quote: Ashleigh Brilliant)
Warranty Fail: Screaming so loud in a high Falsetto voice at Bumrush attacks has crushed the membranes of your 23" superthin monitor screen after the warranty has lapsed due to sonics and micro-reverberations. You now endeavour to yell Offensives in a strong Basso-Profundo to shake the walls instead.
The Delicately Predisposed: You get exeedingly nervous using a scope or binoculars of any sort. There is errant movement in 2/8 bushes and distant panels flicker, distracting you attention. Any one of them could be a potential target. So to be sure you send a few rounds into the offending sprites. Surely enough you are eventually attacked- not by the flickers but by the more sound-sensitive enemies in a five-hundred metre radius.... Also known as the 'I Told You So'

So, Community, what you got? :gun:

Consolectomy: (PC users only) Indiscriminate use of the TCL command results in your companion(s) becoming embedded in 100 feet of granite. Fast travel is now a crap-shoot.

Collectomania - you collect and store in your abode, the many useless things; little blue cars, chess sets, teddy bears, etc etc etc

Represent! You Shoulda seen me in F3... My pad in Megaton had a pyramid of whisky bottles on the internal balcony and I slept on a big pile of pre-war money! *giggle*

school prankster: drowned in the ultra-luxe swimming pool

/rage - have no play-time from Dead Money's release date to the release date your console gets it.

Florence Nightkingale :Listen to Lily say "It's okay dearie, grandma knows how to be quiet" while couched for the millionth time, shoot and heal her.

Sergeant Teddy, Of the U.S.A.!: Amass an army of teddy bears and side with Sergeant Teddy to take Hoover Dam for Teddy Roosevelt.

I collected gnomes... then when it became time to pack up and move to the mansion i had to make two trips because i couldn't carry all of my items as well as my gnomes and didn't have enough patience to walk overcumbered to the gate of megaton... yeah.

Then in real life i started to get the urge to just take peoples garden gnomes.

Anything that Moves: Take both gender-specific perks, then sleep with every prosttute in the game; female, male, robot, ghoul, brahmin...

Here We Go Again- your companion(s) charge(s) off in another direction for the 1000th time while you are attempting to sneak through an interior. This can also unlock The Sound of Silence if said companion(s) is/are Lily and/or ED-E, when their battle cry(ies) go(es) off in your ear yet again in the process.

you are pathetic- get killed by anything lesser than a radscorpion
that unlucky old sun- get killed by the ARCHII blast
weak swimmer- drown
well done, idiot- become an enemy of every faction and town

Confused:
After reading too many different magazines, your brain pulls the trigger due to data overload (two randomly choosen skills of yours swap their values)