When a male invades somebody elses personal space in such a way that they feel uncomfortable about the proximity of his knob to their body even though it is not touching them.
At a train station if you wished to follow somebody through the ticket barriers to avoid paying the fare you could knob worry your way through by following them very closly.
Dave: "I went to london last night and knob worried my way through the gates at King's Cross and saved myself a tenner."
Dave: "I am going knob worrying down the library. Do you want to come?"