glasgow handshake 

To headbutt someone. See also glasgow kiss. Popular in Scotland, apparently.

Hello, Jimmy!

glasgow handshake by Karl Steiger January 31, 2004

Glasgow Handshake 

To smack somebody over the head with a glass bottle.

"D'ye hear Willie's in the hospital wi' some stitches?"
"Naw, what happened?"
"He was badmouthing Tam's bird when she wallopped him one wi' her ginger bottle, a right glasgow handshake"

Glasgow Handshake by Boabby the barman December 19, 2014