As a Temporal Tourist, it's easy to get caught up in the excitement of your destination, but remember: the locals are not just time-traveling spectators, they're also people with feelings and digestive systems.
When visiting the past or future, try not to bring any food items that might be, shall we say, "acquired" during your stay. No bringing of temporal truffles, no sharing of futuristic fondue... you get the idea.
Not only will this ensure a peaceful coexistence with the locals, but it'll also reduce the risk of temporal contamination. Trust us, it's a good thing.