There's a rumor that Google is going to acquire Groupon for a zillion dollars.
I signed up to see what it was about. Naturally I used my mail.yahoo.com junk email address - a disposable digital identity. (If it ever annoys me too much, I will destroy it and create a new Yahoo persona.)
Groupon is a service that sends you spam. You can't opt out of the spam. Oh, and you can never leave. There's no obvious way to delete a Groupon account.
If Google buys Groupon then I will begin disentangling my data from Google. It will be an incontrovertible sign that they've gone off the rails.