Grandbrother

When your 90+ grandmother has conjugal visits in a nursing home and becomes miraculously pregnant, resulting in a baby boy

Dude, last night I had to babysit my grandbrother because my grandmother broke her hip.

by Brent Hammy June 5, 2015

great grandbrother

When your brother marries your great grandma

Here's an example: DON'T FUCKING DO IT. The Great Grandbrother is a disgusting thing.

by Jimmy JuJu November 17, 2017

Grandsister/Grandbrother

When your son/daughter has a baby with your mom/dad, said baby becomes the your grand-sister/grand-brother.

Today I'm taking my Grandsister/Grandbrother to the park.

by Nullivoid December 21, 2020