Passport
I once sent my passport from guantanamo bay(bysecure mail) to the US goverment to try and get some document that would enable me to get a US credit card from my US bank.It disappeared!With a vacation looming this was not good!I rang the Embassy(?) In Kingston Jamaica explanined my problem and was told oh just tell immigration your expected,they will call us!So I flew in without a passport and it took ten minutes in the Embassy to get a nice shiny blue one!!
Returning the same and same aircraft I got to my office to find a nice brown envelope with my original passport!Now I had two!