more than 1 phrase in IMG ALT tag ?

I guess most of us feel like IMG ALT="" tags should reference 1 keyword or keyword phrase. (referring to the image in general)

But think it would hurt if I used more than 1 phrase...and/or used commas as well?

For instance if the image was of a basketball and the domain url was basketballDotCom ...would it be ok to use

IMG ALT="basketball, soccer , nba, basketball"

or would this be bordering on stuffing ?

and/or what about if it were 2 keyword phrases being used with the 1 IMG ALT tag ?

For instance : IMG ALT="play basketball online", "nba basketball hoop"

Google / Bing generally approve ya think? I'm not even sure if they'd approve of comma(s) being used in IMG ALT tags.