The strangest ones I had were both when I asked "what's the time" (I never really ask that because I need to know the time, I usually use it to check if everything is working fine if there have been any network issues).
Command: Alexa, what's the time?
Response: Lavatory (bathroom, toilet ; a room or building equipped with one or more toilets).
(Logs indicated this was misheard as "Alexa, what's the toilet")
Command: Alexa, what's the time?
Response: The Middle Ordovician, the second epoch of the Ordovician period.
(I have actually had this one several times, and it appears to be responding to the question "Alexa, what's the Dyfed")
I have also had several times where Alexa has responded to the "stop" command with advertising blurb about the Echo Dot (mishearing "stop" as "dot") which is doubly funny as it is actually an Echo Dot I am speaking to.