I used to live in Nairobi, and everyone knew that the most dangerous time of year in the Kenyan capital was the build-up to Christmas. Suddenly everyone either had, or needed, extra cash. Crime - muggings, burglary and car-jacking - shot up as robbers preyed on people preparing to head home for the holidays.
I thought of Kenya this morning as I read this unsettling article in Johannesburg. For weeks now, South Africa's airwaves and newspapers have been warning about a possible explosion of xenophobic violence here after the World Cup. Has it already started?
"Explosion" is an overstatement for what's happening right now. But it's worrying nonetheless. Some people make it sound as if a repeat of 2008's vicious wave of attacks on foreigners is inevitable. It's not - but at the same time I'm not convinced by the rather blithe reassurances I've heard from some officials here.
I was in Nelspruit last week and got no sense of any looming tensions between locals and the large number of undocumented Zimbabweans and Mozambicans staying there. But in Cape Town earlier in the month, everyone seemed to be warning of trouble. Our Malawian taxi driver said he and all his friends had packed their suitcases and were ready to bolt, as the euphoria of the tournament wore off and locals started looking for people to blame for the fact that four weeks of football hadn't brought them the wealth or the changes they'd anticipated.
I'm still convinced the World Cup will be a huge success. But xenophobia could yet provide this country and continent with the saddest postscript.