1. the ground-shaking effects one may experience when an obese person is walking near.

2. the shaking, trembling effect one may experience during or after sex with a person who has a large penis.
Every time he walks by, I feel a girthqake.

The size of his unit caused a girthquake. The aftershocks caused my legs to shake for hours.
by Brandoonline April 15, 2011
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Any seismic event caused by ones weight, especially an obese person or obese people
The girthquake from when that fat bitch went by totally spilled my drink
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"How did last night go?"

"I had to ice my vag after he whipped out dat girthquake."
by buttstuff2k16 May 4, 2016
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what happens when overweight people run or jog to get somewhere quickly
Did you see that obese guy running to catch the bus? Total Girthquake!
by Blackmajik December 2, 2006
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1. the reaction you get by inserting your dick into the orifice of your choosing causing an uncontrolled tremor in said partner
2. having sex with a girl that has a seizure upon penetration and tilting her head and riding the aftershocks out keeping in mind to not let her choke on her tounge
1. dude she was fucking tight,i stuck it in and caused a 6.0 girthquake on the richter

2. omfg i stuck my dick in this girl and she had a seizure,so i held on and kept fucking her....i survived the girthquake
by w1thdrawn September 16, 2011
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the type of earthquake that gets extreme ammount of facebook attention within the first ten minutes; not to be confused with a dearthquake which is the type of earthquake that gets extreme media attention
*Facebook*
Craig: #OMG EARTHQUAKE!!!!
Marco: it was only a little girthquake you attention seeking whore
by JaMarko October 21, 2011
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an earthquake or tremor caused by the walking jumping or just general motion cause by a fat person
tom: oh my gosh no! here comes jeffery johnson its gonna be a 10.0 girthquake

bystanders: run!!!!!!!!!!
by tom beotch! November 30, 2006
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