What is Mum Thumb?
1.
When someones mum wont let them do something, even though they are old enough to decide for themselves.
Overbearing, controlling mother.
Similar to being under your girlfriend/wifes thumb.(not cool)
"No way dude, Dave wants to get a tattoo and although he's 19, his mom wont let him"
"He's so under the Mum thumb!"
See
