I am the youngest and I am primarily a 'ler although I love to be on the recieving end also. My Dad used to tickle us when putting us in bed and my brother used to sit on my back and tickle me hard. He drove me nuts.
I don't think there's a correlation between our birth order and tickling preference, because I believe tickle fetish is genetically controlled..
still I think it's an interesting question and I'm excited about the poll results.