I say 'No worries' in lieu of "You're welcome" or "No problem". Unlike 'wanker' I know exactly where I picked this one up!
You ever read the children's book series Animorphs? One of my favorites while growing up; however, I don't think it ever received as much popularity as it deserves. There is still a good section of it at my local public library though.
I thought this was an awesome turn of phrase and started using it. 'No worries' has so much more to offer than 'No problem' or 'You're welcome'. The latter two concern only the immediate situation and the action which prompted the response. 'No worries' is a sort of well-wishing for the rest of this other person's day.