Grandfather-Clock 

When one gets on a table without your pants on, and swing your junk left to right.

I did a Grandfather-Clock to your mom

Grandfather-Clock by FM4k September 7, 2003

Grandfather 

The person who turns you into a man and makes sure you aren't in bad health.

My grandfather is the older version of a badass role model who won't take shit from anybody.

Grandfather by The Jester of Madness! November 4, 2015

Grandfather cock block 

getting cock blocked by an old person.

I was hitting on this fine looking nurse at the old folks home when my grandma told her about me being unemployed.

me: "nice Grandfather cock block g-ma!"

G-ma: "shut up and drink your ovaltine"

Grandfather cock block by silvershamus February 22, 2011

grandfather cock 

When you're trying to shop for some antique grandfather clocks for your paps but then you unfortunately forget the "l" in "grandfather clock" and now you wish you were dead.

Poor Fool: *mistakenly types 'grandfather cock', clicks on 'images'*
*questionable things appear*
Poor Fool: AH DEAR GOD GET THE BLEACH

grandfather cock by Vladdy45 April 26, 2019

grandfatherless

Having no grandfather

Joe Rounsley is grandfatherless

grandfatherless by Guywithallthebitches March 7, 2022

grandfatherphobia 

Being scared of grandfathers.

He hates my grandfather! That must be his grandfatherphobia kickin' in!

grandfatherphobia by Fredick Beanburger April 5, 2022

Mowing My Grandfather's Lawn 

1) Trimming the gray hair out of your pubic hair.

2) Landscaping your pubic region, focusing on off colored hair.

"What are you doing tonight?"

"Probably gonna be Mowing My Grandfather's Lawn, it's getting pretty thick."

Mowing My Grandfather's Lawn by FDPatton July 13, 2012