This word originates from the large Clydesdale horses. They are known for putting in enormous amounts of work with little success.
A clydesdale is a guy who clocks long hours of work with girls and is a cuntmug.
Pete dude...Mike Boden puts in more work than the Budweiser Clysdales and he never pulls. He is living with his 1 month girlfriend next year...fuckin clydesdale stop piggying you cuntmug.