Big Sister Syndrome
When you have always been the one to pick on your siblings with no consequences... and therefore as an adult shamelessly poke at others even when you shouldn’t. Specially when an adult female poked fun and teases others because they never had an older sibling to put them in their place.
My girlfriend won’t stop trying to tickle me when we cuddle and finds it funny. It’s like she has big sister syndrome. Little does she know what’s coming!