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1.
Verb. To yelf is to prod someone in the small of the back with a turgid penis, whilst laying in bed together.

Often this is a hopeful, unspoken gesture intended to instigate sexual gratification, but it may also be a side-effect of morning glory.
Christopher casually yelfed the girl he had hooked up with the previous evening, but she was clearly more interested in sleep than morning sex.
by Paolov March 28, 2008
 
2.
he whom pnws noods not very well
"Yelf u really suck at pwning noods"
by jamesy boi September 23, 2007