Depends on my mood and what's available. Ketchup or mustard is fine, although some sort of non-standard version is preferred (spicy or curry ketchup; honey mustard or some sort of horseradish/wasabi concoction). Gravy or ranch dressing is awesome, but when you do that you have to acknowledge that each fry is probably taking minutes off your lifespan (especially when you demolish an entire plate of Outback Aussie Cheese Fries all by myself... I mean... yourself).

Sriracha ALWAYS works.

At some point in my life, I WILL try poutine.