And we agreed that NATO should be prepared to considered reciprocal reductions in non-strategic nuclear forces deployed in Europe.

WHITEHOUSE: Press Briefing on NATO Defense Capabilities

In his speech, Mr Cameron said changes to health care would be introduced, with the UK getting "better" at "reciprocal charging", charging foreign governments for treatment provided to non-working overseas nationals.

BBC: UK Politics

For non-celebrities, the more common source of fake followers are spam bots which follow users in order to elicit a reciprocal follow, which then allows them to send spammy, direct messages to the Tweeter.

FORBES: Which Startup Bloggers Have The Most Legitimate Twitter Followers?