This was the one that I have used in the past. There were massive staff turnover issues in the team when I joined, I started to take them out to the local pub for lunch, then monthly dinners, then we'd go to various clubs etc. The "expenses" part would cost about £10 each per month (company paid for dinner, we each paid for drinks in the clubs).
When someone in head office questioned it, I pointed out that we had previously been paying £3k a month in recruitment fees alone (before factoring in time wasted, training etc), so the £2.5k per year was quite a bargain.
Not one person resigned in the 2.5 years I was there.
Lots of niggles and issues can get resolved over a steak and chips and a few glasses of sambucca.
If that doesn't work, then shoot them.