When a motorcycle shakes its head. The front forks going from lock to lock.
He got into a big tank slapper and stepped off on the high side.
by John Stewardson January 17, 2004
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When the fuel in a vehicle hits the inside of the tank hard enough to shake it, nearly always cause by making sudden, unplanned turns. Tank slapping is a symptom of bad driving.

Many cars use special baffles to help reduce this.

Can also include the rider's legs on a motorcycle.
Leaving the last bad corner on Snake Pass I missed the apex and over corrected. When the tank started slapping I thought I was a dead man.
by dj_monged August 15, 2004
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The aftermath of a very rare and extraordinary poo. A tank slapper requires the coming together of a unique arrangement of circumstances not encountered on a frequent basis.

Firstly the poo being ejected must be firm, ideally smooth, definitely not sticky and have some elastic properties.

Secondly the body from which the poo is being ejected, must be longitudinally centred and slightly forward on the pan. The sphincter must not be too slack or overly encumbered by anal beard, this is to ensure maximum velosity on exit and reduce any parasitic friction.

If these properties are met, the poo will launch out of the anus. It will hit the forward side of the pan, adjacent to the bowl water. Ricochet on to the back pan, leaving two perfectly vertical skid marks in front and behind the bowl water. This is a tank slapper.
Jeff, Jeff, my legs are trembling and I feel like I’ve been touched by the almighty himself. JEFF, I’ve had a tank slapper.
by Cludgyspanklips September 26, 2021
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see 'Tank Slapping'. The art of anal sex with a man in a doggy style.
Goerge is gay. He is a right tank slapper, he likes being tank slapped balls deep...
by Christoph October 26, 2005
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