They call it the three quarters in union too which is strange.

12 Centre
13. Centre
11 Winger
14 Winger
15 Fullback

If you add 5 and 8 you get 13.. just sayin like..

Fly half/stand off also called out half or outside half in some places down under.

Out 5/8 is sometimes used in Union to describe Inside Centre (12).

Not sure where the description of three-quarters came from as that has been around for donkey's years in both Union and League.

Why is it strange?

Remember in both codes the numbering used to be the same (same us now in league). Union swapped their numbers round at some point in history. Can't remember why now. Other teams used letters to try and confuse the opposition (Welsh sides originally, but more recently leicester but they have since reverted to numbers).

I know a Standoff called Dave

There not halfs, 5/8ths, flyhalfs or scrum halves theyr'e generally refered to as orrible little SH!T$