Our friend and former NASA Engineer turned YouTuber Mark Rober steps in as guest host, conducts an experiment at the Farmer’s Market in LA to see who would recognize him, and in honor of Mark’s upcoming Discovery series “The Revengineers” we set up some ridiculous situations on Hollywood Blvd to see if anybody would stop and do the right thing, and we reward the good Samaritans by giving them the opportunity to blow stuff up for a chance to win some of Jimmy’s money. SUBSCRIBE to get the latest #Kimmel: http://bit.ly/JKLSubscribe Watch Mean Tweets: http://bit.ly/KimmelMT10 Connect with Jimmy Kimmel Live Online: Visit the Jimmy Kimmel Live WEBSITE: http://bit.ly/JKLWebsite Like Jimmy Kimmel on FACEBOOK: http://bit.ly/KimmelFB Like Jimmy Kimmel Live on FACEBOOK: http://bit.ly/JKLFacebook Follow @JimmyKimmel on TWITTER: http://bit.ly/KimmelTW Follow Jimmy Kimmel Live on TWITTER: http://bit.ly/JKLTwitter Follow Jimmy Kimmel Live on INSTAGRAM: http://bit.ly/JKLInstagram About Jimmy Kimmel Live: Jimmy Kimmel serves as host and executive producer of Emmy®-nominated “Jimmy Kimmel Live!,” ABC’s late-night talk show. “Jimmy Kimmel Live!” is well known for its huge viral video successes, with over 11 billion views and more than 15 million subscribers on the show’s YouTube channel. Some of Kimmel’s most popular comedy bits include “Celebrities Read Mean Tweets,” “Lie Witness News,” “Unnecessary Censorship,” “Halloween Candy YouTube Challenge,” and music videos like “I (Wanna) Channing All Over Your Tatum.”