Combine three-bean mix, black beans, pinto beans, corn, tomatoes, tomato sauce, onion, green chilli peppers, green capsicum, taco seasoning and garlic in a slow cooker. Add beer and give mixture a good stir.
Cook on Low until flavours combine, 6 to 8 hours. Serve topped with crushed tortilla chips and green onions.
You can dice the onion, green pepper, and garlic the night before to save time.