Very small bumps(like pimple, without pus) on my penis meatus. visible after ejaculation. no pain or itch. what is it??

Not a concern: If there is no pain and no other part of the glans affected, it is likely nothing to be concerned about...possibly brought out to view by the engorgement/erection process and you see it "after ejaculation". Of course without seeing it, I cant tell you 100%, but sounds to be of no concern and not likely contagious.

PPP?: Likely are pearly penile papules, which are harmless. See: http://pppremoval.Hubpages.Com/hub/pearly-penile-papules-ppp-removal-treatments -- for more information and options on treatment, if desired. If not similar, should see your dr or a urologist for diagnosis and treatment options. Can also google-image for comparison images.