The English sentence is:
If you do something like that, you'll be such a bad* loser.
Meaning that you'll lose badly.
I translated it as:
... Du bist ja ein schlechter Verlierer.
But someone told me, don't use "schlechter" but "guter" instead. Who's a "schlechter Verlierer" and who is a "guter" one? Is there a better translation for what I'm trying to say?
*: What I meant is not that the person as a bad loser, becomes angry when they lose but preventing them from doing it by using the word "bad".