Well, Clint was fairly quick on his feet in terms of witty banter, so it only stood to reason that he had a lot of practice with his tongue. In any case, he wasn't teasing. Not anymore, anyway.
Instead, he went to town like he was on a genuine mission -- pressing forward enough until his nose touched up against Jamie's skin and more or less choking himself until he had to lean back, and then he started all over again until he found a rhythm that made sense with Jamie's rocking hips.