The term used to tell someone that they should deposit some more petrol in the tank of thier car if you are drugged to the eyballs
Person 1 says: Hey your tank is empty, maybe you should fill er up

Person 2 hears: <mumble> fill er up
by Pottsy2 September 6, 2008
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When a man puts his penis into a girls anus and urinates.
She was running a little low, so I had to fill-er-up.
by manbeef November 9, 2004
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When having analingus with a lover... Urinate inside her...
Yeah so I totally pulled the Fill 'er Up on my lady friend.
by Nilam Nad June 20, 2006
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