Sometimes pronounced as the letter "t" and then the word "runner". It describes a very awkward male of about 15 years of age. He is usually a boyfriend that had made very awkward choices in the relationship he had with his girlfriend, and is usually very tall. He runs at a very awkward angle, usually in a slope-forward in almost a jaunty angle. When he runs (which is not often), he almost "bounces", on the tops of his toes, picking his knees up high as he does so. His mother dotes on him.
"oh my GOD, that kid over there who tried to get into your shirt is SUCH A TRUNNER"
"I KNOW! look at how he runs!"