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4.
someone who is tweaking on meth, or seems to be tweaking on meth, or just looks any sorts of sketchy
#thatdudesmerfin
by jackbaraqueer September 07, 2012
 
1.
According to Kellin Quinn from Sleeping With Sirens, "Someone who is tweaking on meth, or seems to be tweaking on meth, or just looks any sorts of sketchy."
THAT DUDE'S MERFIN.
by itsjustangel September 09, 2012
 
2.
An abbr. of motherfucking in an effort to be more politically correct, "PG", or safe for work.
M'er'f'in yessssssss!!!!!

That m'er'f'in bitch was a fucking whore ass dipshit at the party last night.

Mom! I'm on my m'er'f'in way back home. Chill!

Awwww yeahhhhh, m'er'f'in cheeze burgerzzz...
by manofwar July 03, 2014
 
3.
someone who is tweaking on meth, or seems to be tweaking on meth, or just looks any sorts of sketchy
There is this guy sitting behind a bush at that park watching people; that dude's merfin.

Kellin Quinn advocates merfin awareness because no one likes a merf.
by WoahMyNo September 07, 2012