Well, you'd have to tickle every person in the world. The very ticklish ones will generally be the ones opting out of participation. Such a competition would attract non-ticklish people who would simply fake laughs of anticipation and call the safeword before the tickling even begins. At which point, they couldn't be tested ethically. And someone who may be truly "the most ticklish" would potentially do the same thing of calling the safeword out from being overcome by ticklish fear. If we are willing to suspend issues of consent, and assume everyone is honoring the spirit of the competition, I would imagine the next hurdle would be that some people would hold the record for most ticklish body part (I.e. Someone would have the most ticklish underarms, another would have the most ticklish feet, etc). Moreover, there's the psychological aspect of someone being more or less ticklishness depending on who the ler is, and what their mood is, how they're being tickled, etc. There would be a lot of variables. Not as easy as finding, for example, the tallest person in the world. This wasn't a fun answer, was is? HAHAHHAHA