Post Your Coins With Center Holes

Heh-heh. I recognize that mystery coin" right off the bat!

It's a South Korean Busan student city bus token.
In the first pic, "학�" means student, and in the second pic (which is upside-down), it says "부산 시내버스," which means Busan city bus.

An easy tip to identifying it as Korean:
Korean characters have circles and ovals, which are nonexistent in Chinese or Japanese characters.

They seem to come up here once in a while. They sell for about a buck a piece here in Korea.

Holes are put in coins for various reasons.

Colonial regimes in Africa and the Pacific put holes in at least the low-denomination coins so that the locals, whose native dress did not include pockets, could carry them around on strings around their necks. That may sound patronising today, but it was the actual reason stated at the time. Your Southern Rhodesia coin is an example of this.

European early 20th century cupronickel coins are often holed. Very often these holed cupronickel coins replaced unholed silver coins the same size, making the hole a great big impossible-to-miss signpost shouting "this coin is not made of silver". The French, Danish and Norwegian coins probably fall under this category.

Other times, the hole is purely decorative, or used to help both humans and machines easily distinguish two similiar-sized coins from each other. In this sense the holes serve the same purpose as unusual shapes or different edges. The Greek and Spanish coins are in this category.

The holed tokens above are all used in countries (America and South Korea) where none of the actual coinage is holed, so a huge hole shouts "this is a token, not a coin". Some tokens (I'm thinking mainly of certain North American transport tokens and New Zealand milk tokens) have elaborately-shaped voids in them to even more accentuate their non-coin-ness.

What's interesting about the Danish 25 ore is that from 1924 through WWII they were holed. Then from 1948 to 1967, the hole dsappeared, only to make a comeback from 1966 to 1988 (apparently there was an overlap in the styles in 1966-67).

How many different types of World SILVER coins with central hole actually circulated?

I can think of only one type:
The .925 silver shilling of New Guinea.
They are relatively easy to obtain, in Australia, at least. I have all four dates: '35, '36, '38, & '45.

Does the Holey Dollar count?

For both the first and second reasons I gave above, silver coins almost never got themselves holed.

Another reason for a holed coin would be to allow a coin of a specific amount of metal to have a larger diameter. (Coins work best I a certain size range, not too big or too small. If you have too many denominations the difference in sizes can become too slight, so you start adding holes and two coins of the same size can instantly be told apart. You hole the lower denomination or someone might try to pass off a low denomination as a high one by putting a hole in it.)

They also help in value identification in countries where a large percentage of the country is illiterate. Denominations are recognized by size, color, holed or not, etc.

Fork has hole off center.