I think now that you're hearing two different ideas this would be useful:
2--> Urban Dictionary: I'm Good


As for number 1, there's a discussion here, which seems like this user has/had the same confusion as you do now, so i think it's pretty satisfying:

Singular Countable Noun WITHOUT an article!

And again for number 1, i hope it would be a bit relevant:

Can I omit a/an before a singular countable noun? - WordReference Forums

Hopefully, you're less confused now!