Two gentle jokes at the one (Thai) restaurant where I work now:

1) To a table of three (Iranian?) (graduate student types?) who are semi-regular customers, and the female of whom has dyed her hair blue:

Me (to her with concern, after checking with the table in general if everything is okay with their entrees): 

"Are you really sure your food is okay? Your hair turned blue!"

. . .

(Later when they leave, I apologize for our kitchen being radioactive, and its turning her hair blue.)

. . .

2) To a large table of 2 (South Asian) families, to whom I had already shared my joke about the blue hair, after I had made it at the other table:

Me (to the [skinny] [fairly dark] [young] boy, who had wolfed down the dessert that they had let him order): "Wow, you really finished that! You are the smallest one here, but you eat the most!"

. . .

(That last joke got peals of laughter from the [South Asian] adults, especially the mother, who cast me a lasting endearing glance. Gentle humor works so well with them.)