Is it possible for a 3 year old to get an erection?

Yes, it is possible for a 3-year-old to have an erection. This can occur due to natural physiological responses, which are normal in young children. Erections in young boys can happen for various reasons, including stimulation of the genital area, a full bladder, or even spontaneously without any specific cause. It's a normal part of development and typically not associated with sexual arousal at that age.