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A penis which, when no boner is present, appears to be very small. But, when the boner occurs, the penis is much much larger than expected
That girl didn't want to have sex with him because she thought he had a small dick. Yet once her friends who slept with him told her he actually had a sleeper penis, the girl went ahead and had sex with him too.
by BigDaddyDeac December 22, 2014
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