1. A slang term for when a member of ones social circle engages in an act that they would typically be unwilling or unable to participate in due to various limitations.

2. An ironic expression intended to celebrate rowdy behavior by juxtaposing that behavior with the behavioral tendencies of the elderly and enfeebled.
Prsn1: Lets go into town for a late night pub crawl.
Prsn2: Okay, but you know I can't handle alcohol quite like I used to...
Prsn1: Grandma's on the boat!
by Epimone July 5, 2019
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