What to do with 10 liters Heinz BBQ sauce?

'Expiration' dates on anything that's not baby formula aren't. They're 'best used by' or 'sell by', but many restaurants will get rid of it for liability issues.

Although it should be good for many months past that date, it'd be better stored refrigerated, and I suspect most people don't have the fridge space for that sort of thing.

What I'd recommend is finding a soup kitchen or similar near you and donating it. They could slow cook chicken or pork in it for a very easy meal, or even glaze and grill it. If any of the churches near you do big dinners as fund raisers, that's another possibility.

As people have mentioned in the comments, you can freeze whatever you don't use right away.

One caveat with freezing is that when you thaw it out, it might* not be as good to use a condiment. That being said, you could use it as a marinade, a base for a different sauce, as part of a crockpot recipe, or to baste/slather on meat while you grill.

*I say might because depending on the sauce, it could have enough preservatives/coagulants/other science-y stuff in it that it's texture and consistency remain even after being frozen and thawed. Absolute worst case scenario is you now have ~10 liters of marinade in the freezer.

That's going to be a "best before" date, not a "use by" date (if it's the same ketchup-like stuff you get in the supermarket). So assuming it's sealed at the moment, open it when you want to use some, and then get through it within the "after opening" instructions (probably something like "keep in the fridge, use within 4 weeks"). You may need to decant into smaller containers to fit in a domestic fridge; you could also freeze some at that stage.

I would definitely smother it all over whatever you have in your cupboard already. I would start with a packet of Penguins or Tim Tams, they are a great dipping substance.

You are going to be very happy for a very long time! But don’t be careless with it...