Not sure where the pic comes from, but it looks like this is a personal illustration from one web comic artist to another. The character depicted is Raven from a web comic called Lowest Common Denominator (LCD) by Bryan Richter (also known as Bry, the signature on the picture). It was a pretty cool and witty web comic, with occasional tickling mentions and characters. That comic sometimes crossed over into another web comic, Clan of the Cats (COTC), another pretty cool and witty web comic by Jamie Robertson (probably the Jamie referenced in your attached comic). Raven was initially not ticklish at all, but during a crossover with COTC, she was rendered ticklish by a magic spell (way too long a story line to explain). COTC is still active, I believe, and though I think that LCD is now, unfortunately, inactive, I believe it is archived and accessible. Hope this helps!
