I got the wild shites in Belgium.
Little tip: yes, mayonaise with frites is fantastic. Yes, little chip vans by the side of the road and in car parks do wonderful frites.
BUT...if you are visiting the battlefield of Waterloo in March, if you have to wake the man in the car park chip van up (and it's clearly the first time he's opened up since the previous autumn), and the massive vat of mayonnaise was clearly opened a long, long time ago from all the dried slime around the outside...DO NOT insist to your fiance that she 'really must have mayo with your frites' unless you want her puking violently and sufferring rampant diarrhoea for the remainder of your holiday...and then you catch her up 24hours later.
I still remember the terrible, urgent quandry of wondering which imminently projectile end to point at the lavatory first. Sometimes I got it right.