If my future self came back in time, I'd ask two things-
1) "Did my parents put you up to this? Because seriously, that's lame. I've seen that South Park episode- I'm not a dumbarse"
2) Assuming the fat old bastard can prove he's me, I'd ask for the blueprints for his time machine, and the precise date of when he travelled back in time. That way, whatever he's come back to tell me will not have paradoxically robbed himself of the desire and means to come back. All I'd have to do is build the time machine and go back in time regardless of what differences occur between our time lines. Now that's how you do time travel!
"Knowledge is knowing tomato is a fruit. Wisdom is not putting it in fruit salad."
Also known as BaselessElm