Colleague's thought process:

Hmm I have observables but I don't understand shit.
Hey I like listeners let's add listeners to all observables.

Should I make the method return an observable and subscribe my listener to it?

Nah I'll erase everything and pass an anonymous class listener to the method so no one can chain a few calls together.

Fuck you and I hope you're reading this!!!

Time to rerewrite 2k lines of fucking code....