The best pick-up line I've ever heard is in Dutch so it'll need some explaining, it goes:
"Ik heb geen openingszin, maar jij hebt een opening en ik heb zin."
Openingszin is Dutch for pick-up line
Basically, before the comma it reads: "I don't have a pick-up line,..."
The rest of the sentence is a bit of wordplay concerning different meanings of the same word.
'Opening' is rather similar to its English meaning. It can refer to a start, like in 'opening gambit'. An opening is also a word for a hole, be it an opening between a line of troops, the entrance to a tent or a crack in the floor that shows you the floor below.
'Zin' means 'sentence' in Dutch. So 'openingszin' is literally 'starting sentence', so the line with which you start the conversation. The term can be used for any conversation but mostly relates to pick-up lines.
However, 'zin' also means something along the lines of 'wanting something pleasurable'. "Ik heb zin in taart" means "I'd like some cake". Without a topic to refer to in the same or a previous sentence though 'zin' plainly refers to sex. I want to have sex.
So the whole of the above sentence can be translated like: "I don't have a pick-up line, but you've got a hole and I want sex." Much better in Dutch you'll agree.
