noise

The dog is fine, but we've never heard a dog make that sound before. It's like it's coming from the sky.

lol wut? We had no idea they made that noise!

That moment when you're not sure if your housemates heard you having sex or not: you don't know whether they're acting awkward or not, and you're not sure whether you should act awkward or not.

People who aren't awkward don't have this problem, but I don't know anyone like this.

He just needs a little help.

Plans for the next generation of electron microscopes have been dealt a blow by the discovery of an unexpected source of noise that could frustrate efforts to improve resolution to well below the size of an atom.