I actually arrived in New Zealand with mud under my walking boots once - we had been trecking on Rarotonga, Cook Islands the day before, and I had not read the

I actually arrived in New Zealand with mud under my walking boots once - we had been trecking on Rarotonga, Cook Islands the day before, and I had not read the customs rules for NZ before filling in the paper slip, shortly before getting off the plane (if I remember correctly, it was approximately 10 years ago) - I had to wash the soles in a shallow tub with some sort of squishy pillow in it.