What is Nids?
1.
When a person with crabs,pubic hair comes in contact with a persons actual head hair (this person must have nits) after these crabs and nits mate this produces nids.
Basically you have aids in your hair.
Harry has been poking sally and stops to scratch his head making the crabs off sallys pubic hair touch the hair on his head, outcome :
ewww man you have nids !
See