'Resting my dinner' is to rest after eating a lot of food because you're full to the brim. This resting allows your food to settle into you stomach because you can't be bothered to move.
"I'll do my homework in a bit mum, just resting my dinner"
"I'll join you in 20 minutes, just going to rest my dinner"
"I'll join you in 20 minutes, just going to rest my dinner"
by Nowledge_is-key May 12, 2020