Describes one who has half the number of chromosomes that they should have. Akin to calling someone a retard and/or a freak of nature. Can also be used to imply that one is inbred.
Harvesting Haploids is a term that relates to male masturbation - at the height of which haploid cells are expelled at speeds as high as 25miles per hour.
See also gathering gametes
Dick: Hey Peter you want to play some COD?
Peter: Not right now, I'm busy harvesting haploids.