Here's one: https://en.wikipedia.org/wiki/Omagh_bombing

Two: https://www.justice.gov/archive/usao/nye/pr/2012/2012nov08.h...

Three (not sure if the caller was the one planting the bomb here): https://www.theguardian.com/uk-news/2015/may/01/bomb-aimed-a...

Probably not super common but it does happen from time to time. And imagine ignoring a bomb threat and then it's real, you probably would not want to be responsible for that.