The actor had to get hot and steamy with his co-star Genesis Rodriguez in the Spanish-language comedy, but he doesn't think his erotic performance will excite many cinema goers.
During an appearance on the 'Today' show, he said: "This is the most unsexy sex scene ever committed to film. And the silliest I think I have ever seen."
The 44-year-old funnyman plays Armando Alvarez, the heir to a Mexican cattle ranch whose land is threatened by drug traffickers, and he had to learn Spanish before shooting commenced.
Will practiced day and night to master the language because he didn't want to have a bad accent in the film.
He explained: "I started working with a translator a month prior to filming. Then it was just literally every day and every night and then I started dreaming in Spanish. It was just this intense immersion."
Will - who was born in California - got the idea to make a movie in Spanish from watching telenovelas and he thinks 'Casa de mi Padre' is a "groundbreaking" comedy.
He said: "I just had this crazy idea for the longest time. I think from watching telenovellas which we all love. It's one of the comedies that breaks all the rules ... it's a groundbreaking film."