The little Timmy effect is essentially the little Jimmy effect but it benefits a certain age group in general, so for example if a kid were to make a painting and it looks ugly as shit, and the older brother of that kid makes a fucking beautiful work of art the parent would most likely pick the little kids painting to keep him from balling his eyes out.
Brother: Mom look at this thing I made!
Little Brother: Look at mine!
*the little brother shows a disgusting piece of shit ever*
Mom: Hmmm.. I like you little brothers
Brother: Its the fuckin Little Timmy Effect.