Booze
Today marks the anniversary of the death of St. Patrick -- the dude who ridded Ireland of its non-existent snakes (some folks claim it was a metaphor for pagans). In honor of this great feat, people around the world drink green beer and pretend to be Irish. What does that have to do with double entendres? Absolutely nothing, but it's my excuse for the following lame joke:
Two transcription factors are hanging out. One says to the other, "Did you end up scoring with that cis regulatory region you were macking on last night?" The other replies, "Yeah, I gave her the old zinc finger."