My Boyfriend Peed On Me.

I was sucking my boyfriend's dick and he told me to just suck on only the tip cause it felt good and so I did and he came but instead of semen he shot piss all over my face and chest and we were both really confused and we still are. ( luckily we both have a good sense of humor and we laugh about it now but we still have no idea what happened ) I think it had something to do with the tip thing? idk help