Errr... none of the above?
I pronounce it "Teh", a bit like "Terrible" if you were to stop talking after the first 2 letters.
Effectively, it becomes "Te' Forum"
Like 'eh', but with a 't' in front of it. So shorter than 'tear' (as in rip) and an more abrupt ending.
Sounding more like 'bleh', come to think of it.
Agreed, it's pronounced how it's spelt.
Teh to rhyme with yeah.
My wife alays says tea forum which is appropriate considerinf the many discussions on tea.
I'd say "tur"nip "forum" but not quite as urry but not as eh as meh the way i say that anyway.