Both in his film appearances (especially in 'The Butterfly Effect') and in his demeanor as a younger man, Ashton Kutcher has the aura of being the ultimate frat boy back in his university years. That may well be true; he was a member of the Delta Chi fraternity whilst he was at Iowa. The pranks he played as a fraternity brother may have inspired him to create 'Punkd'. That's not to suggest that all of his interests were juvenile - he actually studied biochemical engineering.
Kutcher wasn't fortunate enough to come from a rich family, and so had to get inventive in order to support himself and fund his studies. He would take on the occasional shift in the cereal department at General Mills when the opportunity presented itself. Also, on more than one occasion, he actually sold his own blood for medical research purposes to balance the books!