I guess my longest experience was in Havana back in 2005. I was backpacking in Mexico with only OW tickets and realized Havana was a short flights from Cancun. Bought myself a R/T for a 10 day trip to Cuba and jumped on a plane.
I got off the plane looking like a non-discrete drug smuggler - unshaved, big straw hat, flip flops - you name it.
Two very friendly and young custom officers spent the next two hours going through every single nook and cranny in my luggage. I speak Spanish so we had an interesting conversation about my travels, Cuba, politics and religion. They didn't find anything - and I had superbly nice stay in Cuba.
Other story that comes to mind was crossing the border from the US to Canada driving to Montreal by car. I had my Israeli passport on me and the girl who was driving had her Saudi passport. You can imagine the surprised look on the officer's face. We said "Just don't tell our parents" - he smiled, stamped and let us go
