We found 2 Reddit comments about Tourist Trapped. Here are the top ones, ranked by their Reddit score.
They're available legally on Amazon http://www.amazon.com/Tourist-Trapped/dp/B0097WIK90 and on iTunes https://itunes.apple.com/us/tv-season/gravity-falls-vol.-1/id530179161
If you feel like supporting the creators and animators, you can buy individual episodes for 1.99 on Google Play or Amazon.
They're available legally on Amazon http://www.amazon.com/Tourist-Trapped/dp/B0097WIK90 and on iTunes https://itunes.apple.com/us/tv-season/gravity-falls-vol.-1/id530179161
If you feel like supporting the creators and animators, you can buy individual episodes for 1.99 on Google Play or Amazon.