Cats Do Funny Cats

Why does a cat do a stiff-legged hop/touch against a human?
That is the cat’s body language of saying, “hey, hi there, how ya doin’?”

Why does your cat rub up against you?
Cats have scent glands along the tail, on each side of their head, on their lips, base of their tail, chin, near their sex organs, and between their front paws. They use these glands to scent mark their territory. When the cat rubs you, he is marking you with his scent, claiming you as “his.” Too, he is picking up your scent. Cats rub up against furniture or doorways for the same reason - to mark the item as “his”. (Urine spraying is also a territorial marking, by the way)

Why does a cat sometimes wash its fur immediately after being petted?
There are two theories on this behavior. One theory proposes that the cat is getting rid of the human smell. The other is that the cat is furthering the pleasure of his association with you by tasting your scent.

Why do some cats suck wool or clothing?
There are a couple of theories on this:
The cat was weaned too early and the scent of the lanolin reminds the cat of his mother, or the cat has a lack of fiber in his diet.