Thumb war-
PUA: *Looks at his hand* Wow, that's weird... Hold out your hand a second...
PUA:let me see it *takes her hand in both of his*...
PUA:now do this *arrange her hand and yours so it in the thumb war arrangement*... PUA: one, two, three, four, I declare a thumb war!
Notice how the pick up artist uses small compliance tests and builds it up into what he wants her to do. If you ask her to do a thumb war with you straight off then she might say no but asking her to first "just hold out her hand for a second" is unlikely to get a no. In this way a yes ladder is built up.
*note You can also use this to settle arguments / disputes in a fun way