I have never heard this phrase in my 42 years of life, and to be honest it makes no sense. Can you provide some context please.

I could not think of a situation in which this would be said, so I looked around on Google. It appears to be a phrase some parents use with their children to get them to try new foods. They offer a particular food, and the child may say "no thank you." They would then be given a "no-thank-you helping" which is one or two bites for the child to try without being forced to eat a full serving. It is not a phrase I've ever encountered before, so I wouldn't say it is in common usage generally.