Chris Pratt credits ''monster trucks'' for calming his son's tantrums.

The 'Guardians of the Galaxy' actor settled 23-month-old Jack - who he has with wife Anna Faris - by showing him YouTube videos of the huge vehicles recently and says the little boy is now obsessed with them.

Asked how to calm his son, he told People magazine: ''Monster trucks. He was crying the other day, and I had him on my lap. So we watched this 15-minute highlight reel of Grave Digger on YouTube, and dude, it was so badass!

''He and I both were just wide-eyed. Now he goes around saying,'Monster trucks, monster trucks!' ''

The 'Parks and Recreation' star transformed his physique to land his role in 'Guardians of the Galaxy' but joked he landed the part of Peter Quill by being himself.

He quipped: ''Just be yourself, and hopefully they can shape an epic space adventure around exactly who you are.''

The 35-year-old actor is thrilled 'Guardians of the Galaxy' has already proved to be a hit, bringing in $94 million at the North American box office over the weekend.

He wrote on Facebook: '''Thank you everyone watching #GuardiansOfTheGalaxy this weekend!. We're all so happy that people are loving it.

''Stay for the credits, not just the awesome post credit sequence but to read the hundreds if not thousands of names responsible for bringing it to the screen. #grateful (sic)''