Readers have told us that the term 'doughnut' in respect of bonuses is the visual equivalent to an onomatopoeic word - a big fat zero (although some thought that the term originated over at retail chain B&Q, which is alleged to have at one time advised staff that they were to get decent bonuses, only to hand out doughnuts instead!).
In the US, of course, doughnuts (or donuts) are round, with a hole in the middle - just like a 'zero'. And our US cousins have apparently used the term 'bagels' for years in tennis, to signify a game, set or match lost to love (zero points).
One wag told us that at one stage a few years back, staff at HSBC referred to their end of year 'payouts' as 'bofnuses' - because everyone knew that there was no 'f' in bonuses! Another suggested that relatively small bonuses paid to staff at French banks should perhaps be referred to as 'croissants' instead.
The term doughnut, so you told us, is also used in broking. Having a 'doughnut' day means a zero day in terms of sales commission. Two zero days are a 'James Bond' (007), three are known as a Magic (after the 1975 UK hit single by Pilot 'Oh, Oh, Oh, It's Magic'). Four zero days are known as an 'Audi', after the car firm's logo, and five are known as an 'Olympic', for obvious reasons. Six is called 'the sack', as you probably don't get to stay employed if you bag a sixth zero day running!
We also learned that a £1m bonus is known as a 'bar' (probably a reference to 'gold bars'). A £250,000 bonus is a quarter bar, half a bar is £500,000, 10 bars is £10m and, if you are really coining it, you get a 'vault'.