He acted as a 'foil for' the comedian. [=he acted very serious to make the comedian seem funnier]
His reserved manner was a perfect 'foil for/to' her bubbly personality.
That dark blue dress is good 'foil for' her blonde hair.
(..) this afternoon in the Southland. The LAPD rescued a local man from the Hollywood sign, the city's only real landmark. They actually wrapped you in a foil blanket! Did you run a marathon before this? - Okay. Give me... - No! - No, no. I wanna save it. I gotta save it. - No. That's enough! - Give me the remote! Shut up! - No, I wanna watch it over and over. Foil wrapper... Okay, okay, okay, okay, okay. It's okay, it'll be up on YouTube. Hey, you're still good to take Dad that week I have to go to DC for Sam's class trip, right? - Yeah, he's gonna stay with me in New York. (..)2011 Friends with Benefits