It's not as weird as it sounds. Avocados have a seed so they are technically a fruit. And my friend Jessica just had a tomato (seeds!) and cucumber (seeds!) smoothie in Belize. And while we are all used to them as guacamole, they lend themselves well to a bit of sweetness. Have an avocado smoothie for breakfast, and you'll actually survive until lunch without a terrible case of the munchies.
Combine one firm avocado with cold almond milk and about one tablespoon of honey or more if you like sweeter smoothies. Toss in some sunflower seeds or other nuts if you like. I prefer to garnish it with some crunchy caramelized sunflower seeds but that is a bit of extra work.
If you like it, awesome. If you don't, go back to your guac. Zzzzzz!