This might be a stab in the dark, but perhaps it simply means "tea or coffee"? Tea = herbal Coffee = leaded in the sense of petrol/gasoline, ie. it stimulates you and makes you go.

Yes very strange, I have also not heard that before. In SA when we ask for tea, we may ask for herbal or "English" tea.

As a native speaker of Australian english, i have never heard this phrase before...over here, leaded means "containing lead" (the metal; eg "leaded petrol") - you definitely do not want to drink that!