To childishly pursue a not-entirely unwilling potential sexual partner with one's engorged member in an inappropriate location, at an unseemly time or in inadvisable company.
The very adult equivalent of the significantly more innocent pubescent pass-time known as 'Kiss-chase'.
'What's up, A? You look a little down today.'
'Saw Gemma last night... You know how hot she is.'
'Exactly. So we kind of have a good thing going on... but it seems like someone up there's got it in for me. Wrong time, wrong place, too wasted, no place to go... You know the score. So last night I'm there, she's beautiful, i'm in the moment - well, I'm always in the moment - and then-'
'Say no more. Cock-chase?'