Is it illegal to use somebody's library card to use the Internet minutes?

Yes I used to do it all the time.

Well, as long as there is no one else waiting to use the machines.

Take a little risk and use it! I’m sure it’s not necessarily ethical but if your friend gave you permission, it seems okay to me.

Yes, as long as you have permission.

why not? It also helps obscure identity if you want to ask embarrassing Qs about crotch rot strange sex activities or look up really tacky stuff for sale. The trackers won’t know it’s you.

I think the proper question to ask is do any of the library staff give a shit?
The answer is no.