Yeah, well-targeted poking can be devastating -- one or two well-aimed fingers can elicit wildly disproportionate twitching and yelping from me -- which of course is embarrassing and (worse) greatly entertaining to everyone in attendance, inviting mortifying group commentary on my level of ticklishness and/or further pokings until I twist and squirm away.
I've actually found that some people in platonic, vanilla settings are likely to use poking as a socially acceptable gateway to tickling, a test case, a firing across the bow -- it's not inappropriate for friends, friendly acquaintances, or even friendly professional colleagues to give one another a gentle poke to punctuate a moment of joking or teasing, and then if that poke sets off ticklish fireworks, as in my case, future ticklings often follow...