Maybe not oddball syntax, but rather syntax that doesn't make intuitive sense. With Python, only nested list comprehensions come to my mind that are a bit trick

Maybe not oddball syntax, but rather syntax that doesn't make intuitive sense. With Python, only nested list comprehensions come to my mind that are a bit tricky to read. With Ruby, I often felt lost reading code and it was sometimes hard to figure out the name of a thing or search for a specific syntax, e.g. with a single character like @ - especially in the official reference documentation. But maybe it's on me for not learning Ruby properly first.