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A comically large shlong, capable of filling an over sized condom with disturbing ease.
As a pickup line:

<drops magnum condom in front of hot, yet sufficiently easy woman>

"Oh whoops… I dropped my monster condom that I use for my magnum dong."

As demonstrated by Frank Danny DeVito in "It's Always Sunny in Philadelphia".
by Rationalize October 10, 2011
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