Answer by Kaushik Parashar:
Most probably, the tiger will laugh. Well, not the technical 'laughter', but possibly a positive vocalization or an expression of joy.
In an attempt to understand the origins of laughter, Dr. Marina Davila-Ross and her team has been studying tickling in a lot of animals lately. They have studied positive vocalizations in primates and based on their study, they have concluded that laughter is at least 30 to 60 million years old. Earlier in 2003, Panksepp and Burgdorf  found that rats laugh when tickled and they enjoy getting tickled. That opens up a huge range of animals who may laugh when tickled. So now the team is gathering and comparing tickle laughter in as many animals as possible.
As for the tiger, I am not sure if they have a tiger laughter video yet. But looking at this lion,
and its cousin cats, it seems likely they would laugh.
Moreover, when this camel,
the slow loris,
and now even the toad
http://www.youtube.com/watch?feature=player_embedded&v=00jrXRMlZOYare laughing, don't you think an animal in a striped coat could laugh?
So in case you are able to make a tiger to laugh, you may contactand help contribute in the research. ( )
Disclaimer: This answer in no way encourages the reader to go tickle a tiger.