Marijuana-smoking, slacker pizza delivery driver in Grand Rapids Nick (Jesse Eisenberg) has trouble completing the "30 Minutes Or Less" policy and is reprimanded by his boss Chris (Brett Gelman). Nick's school teacher friend Chet (Aziz Ansari) discovers that Nick slept with his twin sister, Kate, (Dilshad Vadsaria) on the night of their high school graduation, causing Nick and Chet to end their friendship. Dwayne King (Danny McBride) and Travis Cord (Nick Swardson), are miserable living under the shadow of Dwayne's domineering father the Major (Fred Ward). Dwayne confides in lap-dancer Juicy (Bianca Kajlich) about his contempt for his father and Dwayne's presumed inheritance. At Travis's suggestion, he and Dwayne devise a plot to kidnap a complete stranger and strap a remote-controlled bomb to his chest. They order a pizza and wait for a driver to come to their hideout. When Nick arrives, Dwayne and Travis assault him and knock him unconscious.
When Nick wakes up, he finds a vest rigged with explosives strapped and buckled onto his torso,with both a timer and a cellular phone-activated trigger. Dwayne and Travis tell him his situation: the bomb will detonate unless he robs a bank within 10 hours. They also threaten to detonate the bomb if Nick bothers the police. He goes to Chet's school job and alerts him the situation, to which he reluctantly accepts. En route to the bank, Nick manages to quit his job and then goes to see Kate for the last time. Nick and Chet hold up the bank and obtain money while the bank manager pulls the alarm, forcing Nick and Chet to flee quickly. Dwayne says he and Travis will meet Nick at an abandoned rail-yard to make the exchange. Dwayne and Travis go to a restaurant instead as Dwayne calls up Juicy to get her hit-man ally and to head to the rail-yard. Juicy and the hit-man Chango (Michael Pe単a) arrive to pick up the money. Nick hands Chango the money and expects Chango to give him the code which will deactivate the bomb. However, Chet appears and strikes Chango with a metal bar while Nick incapacitates Juicy. The two grab the money and escape.
Overly frustrated by the turn of events and when Nick refuses to answer the phone again, Dwayne activates the speed dial number on his phone for the bomb to explode, but Travis alters the numbers. Rethinking their plan,he and Dwayne head to Kate's apartment in their masks and kidnap her. Chango breaks into the Major's house to find information regarding Dwayne's location and finds a hand-drawn map to the scrapyard. While there, the Major attacks him with a pen gun. The Major is then shot by Chango after a struggle. Upon applying some peroxide, Chango uses the information he found in Dwayne's room to head to the scrapyard. Dwayne threatens to kill Kate unless Nick meets up with him at the scrapyard.
At the scrapyard, Dwayne gives Nick the code 69 69 69 to deactivate and unbuckle the bomb with just minutes to spare. Dwayne has them at gunpoint but Nick has Chet fake having a sniper on them by pointing with his laser pointer. After believing him, Dwayne and Travis drop their weapons and leave with the money. However, Nick is knocked out by Chango who now has Dwayne at gunpoint, demanding for the money. Dwayne gives him the money but Chango decides to still kill him and is torched with a flamethrower by Travis. While being burned on the ground, Chango wounds Dwayne and shoots the gas tank on Travis's back, causing it to explode. Nick takes the money and leaves with Kate and Chet. Dwayne chases after Nick and steal the money and when he has Nick at gunpoint his van explodes, seemingly killing him. Nick reveals he reactivated the bomb and put it in Dwayne's van. While Chet looks at the money, it squirts blue dye on his face. In a post-credits scene, Dwayne (who survived the explosion), Travis, the Major recuperating in a wheelchair, and Juicy are seen in an advertisement for their new family business called "Major Tan: Tanning Salon."

Question: Why did Dwayne's van explode?
Answer: Nick had  activated the bomb and put into Dwayne's van.
Alternative answer: The bomb was reactivated and placed in the van.