If you pick on someone, you repeatedly treat them badly or criticize them.
If you pick out something, you choose or select it.
pick up (1)
If you pick up something, you take hold of it and lift it up.
pick up (2)
If you pick someone up, you meet them somewhere in order to give them a lift somewhere else.
piss about INFORMAL
to waste time or act in a stupid way
If someone pisses you off, they annoy you.
play around (1)
to waste time by being silly or stupid
Play around (2) INFORMAL
to have sex with someone other than one's spouse or partner
to play something that's just been recorded, such as a video, a message, or some music
to try to make something seem less important or less damaging than it really is