A non human adaptive behaviour with a spandrel
One of the first example of spandrel that has been suggested by Gould was the genitalia of hyenas. At the time the term was created, behavioural consequences of having a big brain was a common example and of course, this does not concern only humans but many other animals.

The riddles on the knuckles is another example (that is not specific to humans only either). Those riddles are a by-product of the need the make movement with your fingers. 

I am personally not a big fan of the term spandrel as used in evolutionary biology. This term easily leads to limit cases and it depends on how you define the phenotypic traits and the functions they serve.