After decades of dining in delis, lunch counters, bars, etc. have seen ketchup and mustard bottles unrefrigerated at the service stations so they must be alright at room temp...prime ingredient in both is vinegar, so there.
Speaking of vinegar, don’t pour out pickle juice.
Use a cup (or more) when slow cooking a roast.
Flavors salads.
Cut up a cucumber into some to make more pickles.
Some people like it on shaved ice.
Ok, you can pour it down the sink to clear pipes as a substitute for the vinegar.