postincidence 

An otherwise unrelated post that addresses the post appearing directly above it in a social media feed.

Sally: "I posted on Facebook that I need a new computer."

Harry: "Yeah, in a bizarre postincidence there was something about an Apple giveaway right under your post. I sent you the link."

postincidence by zerz July 16, 2013

Pushincidence 

When one pushes a button and a unrelated sound or event happens at that exact moment.

I love a good pushincidence. Just now, I happened to push the enter button on my keyboard and the phone rang at that exact same moment.

Pushincidence by Hermes The Geek October 18, 2013