Big brother syndrome 

The opposite of the 'little brother syndrome'.

Man he is always so strange around his brother...

Gotta be the big brother syndrome, he has had this ever since his little brother surpassed him in school performance.

Big brother syndrome by micom1318 January 26, 2014

Big brother meat head syndrome 

When you become so buff meat starts spreading to your brain and you don't know how to think anymore. You also starts drooling and sweating when ever you try to think, signs and symptoms would be saying the word dur consecutively and you begin having trouble forming proper sentences.

man after Wilson went to the gym he started developing big brother meat head syndrome

Big brother meat head syndrome by Gym Teacher Mr. G September 7, 2018