One of my players, a rogue/shadowdancer, with no backstory or roleplay relating to martial arts, monastic training or anything of the sort, wishes to take a few monk levels.
I've said that he'll need three months of training from a sensei to get the first level (which would occur during downtime), and ongoing training for the rest. And that he'll have to maintain a lawful alignment of course.
Interested to know how relaxed other DMs are about random tangent multiclassing. I mean, its what the player wants for their character, it contributes in a big way to his enjoyment, but at the same time you don't want it to be too much of a karate kid montage for realism's sake.