I read in a magazine, quite a while back. and it mentioned that Gwen Stefani has ticklish armpits. Hope that helps. By the way I think it was "Heat" magazine. But I'm not 100% on the magazine title name.
I read in "Heat" magazine about 6months ago that Gwen Stefani is ticklish armpits, and before when she used to date that guy from the band he used to tickle her a lot. Hope that helps