“Before you go into that room I have to tell you something!”

“You’re… me? How did…?”

“No time: I time travelled back five years to–”

“Yeah sure.”

How often do you travel back in time to give yourself the single most important piece of advice ever, only not to trust yourself? Maybe if you show yourself the device…?

“See this? It’s from the future. The guy in there is going to try to give it to you. Whatever you do, whatever he offers, don’t agree to take it.”

“But you took it?”

“Well yes, but listen –”

“Why would I trust you? You’ve treated me badly all my life! Laters.”

You now regret not listening to your future self when you travelled back to advise yourself to bring a stun gun and do the job yourself. And you know you’re going to come back to say “I told you so”.