Noun. 1) The large penis of a racing horse. 2) A penis comparable in size to the penis of a racing horse.
Coined at Poplicks.com: http://poplicks.com/2008/07/what-if-war-broke-out-over-condom-ads.html
Before Mary decided to saddle up to the stud, she made sure to pack some extra-large condoms that would fit his equestriaschlong.