My Amusing Customs Anecdotes:
Boulougne-Sur-Mer, France, 1996. Mum and I had just gotten off the Ferry from Folkestone, and were following the sign that set “Douane et Sortie” (Immigration and Exit), along with everyone else on the Ferry.
Passport Control at the Boulougne Ferry Terminal consisted of the most bored gendarme I have ever seen, standing at a small podium and barely looking at anyone as we filed past- I wouldn’t at all be surprised to discover he was reading L’Express or Le Figaro.
Anyway, a few seconds later, Mum and I find ourselves outside in Boulougne- ie, in France- and stand there looking at each other saying “Was that Customs?”. Turned out that yes, it was Customs, and the French really didn’t seem to care who came into our out of La Belle France.
Channel Tunnel, UK, 1998 (First trip). Dad and I were on a bus about to board Le Shuttle for a trip to Calais via the Channel Tunnel. The UK Immigration people stamped our Passports, and then about 10m down the road the French Immigration officer boarded the bus. He glanced- and I do mean glanced- at the covers of our passports, and waved us on with a typically Gallic handwave. Once again, the impression is that as long as you have A Passport- could be anyone’s, really- the French Immigration Service really don’t care.
(Second Trip) Mum, Dad, my brother, and I are all on a bus doing the same trip to Calais some 3 months later. Bus Driver pulls up outside the French Customs Booth and says “Everyone on board is English, Guv” to which the French Immigration Officer just nods and waves the bus through- even though the bus was chock-full of people on Non-EU passports! :eek:
My brother and Mum were annoyed because they didn’t get the Channel Tunnel passport stamp out of it, either. 
The funny thing was that HM Customs & Excise wanted to give everyone who looked “Foreign” the 3rd Degree, but all three times I came back the formalities consisted of
“Been to France, then Sir?”
“Indeed I have. Nice to be back in the UK, though!”
“Right you are, Sir. Have a nice day. NEXT!”
I imagine it’s changed a bit now, though…