After i pee when i squeeze the head of my penis, i see bubbles and a bit of grey for some reason, why does this happen, is it the movements that create little bubbles? this is right after i urinate?

I assume you have no STDs,no burning on urination,normal stream & no pus discharge. If so,I think you're milking out a tiny amount of urine left in the urethra after urinating. The gray matter may be some mucus. If you still have concerns, consult a urologist for evaluation & advice. Any appropriate testing will be ordered.

Drink plenty of water and dont sqeeze the head of your penis. If it still happens pl see a Urologist