The Only Child Effect Share definition Flag When someone is extremely spoiled or is a huge bitch as a result of being an only child. Why is that kid such an ass? Oh he is always like that. It is the only child effect. The Only Child Effect by TehRealBigDoge April 7, 2015 0 0 Get merch Get the The Only Child Effect mug. Buy Now — $32.95 See more merch