Around 2006-2007, it was a bit of a fashion to hook lava lamps up to the build server.
Normally, the green lava lamp would be on, but if the build failed, it would turn off and the red lava lamp would turn on.
By coincidence, I've actually met, about that time, (probably) the first person to hook up a lava lamp to a build server.
It was Alberto Savoia, who'd founded a testing tools company
(that did some very interesting things around generative testing that have basically never been noticed).
Alberto had noticed that people did not react with any urgency when the build broke.
They'd check in broken code and go off to something else,
only reacting to the breakage they'd caused when some other programmer pulled the change and had problems.