Probably not useful. But its fun so why not!
You have a hotel with infinite room and each room has a guest. A room can only have a single guest. A new guest shows up. Can you provide a room for this new guest?
Yes. Just take the person from the first room and move him to the next room. Move the person from the next room to the third room and so on. Now you have a spare room (first) for the new guest. In fact you can take infinite guests.
1 + ∞ = ∞,
∞ + ∞ = ∞. There is lots of more weird stuff around ∞.