[dylanz]

I have another anecdote. I saw a friend I haven't seen in over a year randomly at the airport. We had a drink, never took out our phones, and he told me he was going to take photos in the Yukon. Later that day on my phone I got an ad on Instagram for "Visit the Yukon!". That creeped me out a bit.

[pavel_lishin]

The obvious conclusion is that the Yukon tourism board, after paying Instagram to show you the ad, also paid your friend to "randomly" connect with you at the airport and try to further sell you on the Yukon trip.

[aembleton]

Your friend searched for Yukon. Facebook/Instagram knows that you are friends and that you were both in the same location and so showed you Yukon adverts.