Will anything bad happen if I drink pure aloe vera from the plant?

safe if not allergic. The rind/skin of aloe has a laxative effect ; is best avoided but the inner gel is very safe unless you're allergic to it. There is evidence supporting a wide range of benefits of drinking aloe- it can boost immunity, reduce inflammation, treat diabetes, lower cholesterol, treat ulcers, irritable bowel syndrome ; colitis, kill cancer cells, treat heartburn, thin blood, lower blood pressure etc.See comment:.
Maybe. Some people experience a laxative effect from aloe vera that can cause diarrhea and abdominal cramping. The health benefits of drinking aloe vera are inconclusive so don't bother.