This is a pretty good read:
https://www.washingtonpost.com/lifestyle/magazine/how-an-undocumented-irish-immigrant-became-an-unofficial-us-diplomat/2018/03/07/58766a64-1324-11e8-9065-e55346f6de81_story.html?utm_term=.b90ebe04c971
He was able to spot his contact in a Dublin pub given the info that he'd be drinking a pint of Guiness and reading the Irish Times?