Originally Posted by perseus11

Simple solution. Just keep getting up and down every minute or so, bumping him slightly as you move. Also lean all the way over and look out the window a few times, with the remark,"Hey look another airplane out there in the sky".

Originally Posted by MSPeconomist

You could jump into the conversation and sabotage his attempt at flirtation if it amuses you. A few witty remarks might send him back to his seat in embarrassment, tail between his legs.