Just kidding, but for real there are challenges to using avocados. They are high in fat. This will likely kill any head on the beer. This isn't a make or break situation, but it might be for some people.
And as already mentioned you might want to try dunking some avocado in a beer to see how it tastes. The avocado won't be used for fermenting, as it's not got much fermentables (I don't think...) so it might be ok for late boil addition or "dry avocadoing" for flavor. Try it with a few different beer styles. My gut feeling is that it might be better in a darker beer, or maybe a beer with less hops and more malt backbone.
But to be honest, I can't imagine the buttery green flavor of avocado pairing well in a beer. We won't know until someone tries it, though. I bet using hops in beer seemed like a crazy idea to our ancestors.