Driver failed to utilize his left turn signal when pulling out of parking lot. I was driver across the stress turning right, pulling out of a different parking lot. We both stopped at the same time and then pulled into the intersection at the same time. However, as he did not use a turn signal, it was assumed he was going straight not turning left, in the same direction as me. Driver pulled window down to yell profanities at upcoming red light (in which he did utilize turn signal this time, after I brought to his attention his error).