Based on the video of Lay as a child in Happy Camp 2012. 

Jongdae bumped his shoulders with Yixing's. "I never knew you were a star gege."

Yixing blushed slightly. "I wasn't really." He mumbled.

Jongdae shoved him with a smile. "Don't be so modest! You totally were a star, like you were on tv and everything. You're famous."

"Jongdae~" Yixing whined.

But Jongdae just laughed at him. "I mean you're famous now but you were famous before." He got out an imaginary pen and pad. "Lay oppa~ Lay oppa, please give me your autograph!!"

Yixing's blush deepened as he tried to fend off Jongdae. "Jongdae please, stop calling me oppa."

"You're right, I should call you sunbaenim." He proceeded to laugh as Yixing stomped his feet and whined. "Sunbaenim, you were really cute when you were young." He pinched Yixing's cheek and ruffled his hair before running away.

"Yah Jongdae!"

Even as he chased Jongdae, he couldn't help but feel a little happy that Jongdae was paying so much attention to him.