Heehee, I love it, but I can't help thinking that with Natasha she wouldn't just say it, it'd be a thing she'd do, or make it so she could stand by and watch Clint do it. I think she definitely says it not just to make Clint smile but also to wind Loki up with Clint's smile though...

Your Business Dress, So Businesslike by gelbes_gilatier is a fun take on that scene :)