Kenzie Taylor somewhat has this habit. Best example I can think of is her blowbang on dogfart. She's chuckling throughout the entire last 5 or so minutes while all of the guys cum into her mouth/down her throat. They're mostly big loads and the crew does a good job of shooting right to the back of her throat, so she even chokes on a few of them. Laughs the whole time, though. It was weird in a very good way to me, haha.

[Link]