Top Definition
A beast with the world's largest 5 inch penis. It should be noted that the 5 inches is in reference to the radius of the penis. When erect, it can extend up to 15 kilometers in length.

The word "Penis-" is the latin word for "Tail" and the term "rex" is also from the latin word "king". Hence "Penis King"

Kingdom - Anamalia
Phylum - Chordata
Class - Mammalia
Order - Penisauria
Family - Penisauridae
Genus - Penisaurus

Penisaurus rex is often abbreviated to P-Rex. The P-Rex is often synonymous with the word AVBP.

The most common prey for the Penisaurus rex is the Danfag

In some cultures, the P-Rex is referred to as "Moosa, the beast with the 2.5 ton AVBP". It sometimes suffers from back problems.
The Penisaurus rex used its AVBP to crush the Danfag

Johnny is the Penisaurus rex.

Occasionally, the Penisaurus rex would suffer from Penisclerosis and would get a 28 hour erection.

When the P-Rex caught a case of Penisclerosis, it used its AVBP to smack Danfags across the face.

People worship the Penisaurus rex by repeatedly chanting "Moosa-Bhai!! Moosa-Bhai!!"
by boringtimes January 31, 2010

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the condition of a mans penis after he ejaculates
his penis is so small when it's in it's penisaurus rex mode.
by boomchild56 December 15, 2014

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1. The mightiest of all prehistoric creatures that roamed the Earth and even Mars.

2. A name given to a man by other men, because even they can recognize that he is better than them.
1. The Penisaurus Rex slowly devoured what was left of the Loch Ness Monster after it dared to challenge him.

2. Man 1: "dude, Robby is such a penisaurus rex.

Man 2: "I know! He is so much better than us."
by penisaurusrex October 30, 2011

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1.An ancient entity part of a race of dinosaur known as <i>penisuclus erectamonus</i>.

2.Christopher Walken.

3.In other words, a penisaurus rex.
Dennis has claimed to have spotted the fluids of a rare penisaurus rex.

"Oh my, its so large and shapeful. Just look at its curvy features."
by Typhoon G. Nguyen May 23, 2008

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