Advertising is most effective when it surprises you with something you didn’t see at the first glance or when it catches you off-guard in a way you didn’t expect.

This cluster features 23 such ads that went for an unusual and creative way to reach out to potential customers.

The ideas include ads with hidden images that only show in the dark, ads posing as editorials in fashion magazines, recruitment ads that are hidden inside computer games, campaigns that stealthily send Bluetooth messages to the phones of passersby, billboards that are hidden inside giant eggshells, and billboards that start out blank and then grow their message with lettuce.