[Oh, he got a laugh. Almost. He'll take that as a small private victory, though it's made perhaps slightly less private by the smile that creeps onto his face while Sanzo composes himself.

Though it's immediately replaced by a still amused, but also somewhat doubtful look at Sanzo's warning.]

Mmm, I think I'll take my chances. But I'm flattered you're so concerned about my wellbeing. [What's fun without a little risk? Ren definitely isn't interested in actually dying, but he's never had a problem with running along the edge of it on his own terms.] Speaking of things like that, are you going to give me a name, or am I going to be calling you Grumpy-san forever...?

[Granted, he may well still call him Grumpy-san forever anyway, but the implication that he won't might work in his favour here...]