Pot - makes me more ticklish and just generally serves as a really cool enhancement to the experience.
Alcohol - brings out the ler in me but isn't all that great for being on the receiving end.
PCP - Holy crap, is that stuff still around? I did some in the 70s. We called it "dust." Not the kind of thing to do often, that's for sure. I wouldn't recommend it for tickling.
LSD - I took my first acid trip in the spring of 1973. I was finishing up 10th grade. I'd recently been in an auto/bicycle accident and was wearing two casts and using crutches. I was watching Star Trek (Arena) and freaking out over the intense colors when my older sister sat on the couch next to me and started tickling me. That was intense.
Cocaine - Definitely good for tickling, but only during the upside of the buzz. When you're coming down, everything sucks, which is why cocaine sucks.
Heroine - Never shot it, only snorted it on two occasions while serving in Okinawa. I decided anything that felt ThAT good was just too scary. Tickling while on H would be irrelevant. Your body is already buzzing full tilt.
Crystal Meth - Like cocaine but dirtier feeling.
White Crosses (speed) - Great for tickling. Your blood is flowing, you're alert to all sensation. Ticklishness is increased.
Nitrous Oxide - Great buzz but too short lived to incorporate tickling.
Pentathol - Wonderful high but too numbing for tickling. Don't try this unless administered by an anesthesiologist.
Amyl Nitrate - I didn't like it. Made me feel hot all over. No good for tickling.
Mescaline, Peyote, and shrooms - If it's a good trip, go for the tickling. If you're already sad, upset, or depressed about something stay away from them.
Painkillers and muscle relaxers - They tend to deaden sensation so I don't recommend them for tickling.
Never did crack or X, so I can't speak for them.