The story
- Middle English · inherited frompilkoc
- English todaypillicock
From Middle English pilkoc, equivalent to an uncertain first element + cock (“a male chicken; slang term for a penis”). Compare the earlier surname Pylcock etc., as well as pillock, Scots pillie (“a penis”), Jutland regional Danish piller and pillerkok (“a penis”), regional Norwegian pill (“a penis”), and Swedish pillesnopp (“wiener, (small) penis”).
Etymology from Wiktionary, CC BY-SA 4.0.