Haha nah I guess I'd just be kinda laughing with them and just goofing around in general. I can't really say what 'lines' I'd use as it would depend on the situation and it's a kinda spur of the moment type of thing.
the best one i can think of is when your tickling someone and you've got their spot and they're freaking out and you just say "oh, just let me know if it's tickling too much... no seriously if it's too much just let me know..." and keep going while they scream and squirm
for me when im tied up and just getting my soles tickled with a feather, gently stroking up my soles, twitching away, saying coochy coochy coo ohhh i start turning into butter melting away in laughter
It's been interesting reading all of these. I can't say that I have a "favorite" phrase myself, though I am a little partial to the simple "kitchy kitchy koo", but what turns me on in both giving and receiving is having the tickler leaning in close to the 'lee and just whispering in the ear anything about teasing, tickling, can't get away, I'll never stop, you're all mine now......you get the idea. That breathy taunt just drives me nuts!
"Shhhhhhhhhhhhhhh!!!!!! You'd better be more quiet or they'll hear you! You don't want anyone to KNOW how TICKLISH you are, do you?!!" Why are you screaming? Why are you screaming?!
Sometimes a hand over the mouth makes them (the 'lee) go absolutely bonkers!!