If someone does something snoopily, they do it in a way that shows they are trying to find out things that are not their business.
Doing things snoopily is usually not very nice. It can make people feel like their privacy is not safe.
Examples:
She looked snoopily through my things.
He asked snoopily about my friend.
The cat watched snoopily from the window.
The dog snoopily sniffed around the room.
The detective snoopily searched for clues.
The nosy neighbor snoopily peeked over the fence.