At the BAD Bistro on Balding Avenue, get a job as a chef by passing the cook's memory test. Go to the BAD bigwig and get his wine glass. Instead of refilling it, take it (with his fingerprint) out through the stove vent in the kitchen, escaping across the ceiling lights.
From the agent in the B.A.D. Bistro. Get the job there as a chef and then get his wine glass (with his fingerprint). Sneak out through the kitchen vent and across the light fixtures.
Besides the spy that is in the garbage can at the docks (who gives you the Bistro code), there is a spy on top of a building by HQ that will give you a clue that will say something like To access the top B.A.D. headquarters, you need the main guy's fingerprint.
The B.A.D. Bistro is on Balding Avenue. To get the Fingerprint of the bigwig there, get the job as a chef. When you get the wine glass, escape through the kitchen vent, then across the ceiling lights to the exit.
On Spy Island, rescue the three kidnapped spies, get the Fingerprint from the Bistro, and reach the satellite control center to stop the B.A.D. scheme. (see the related question below)
There is only one Fingerprint, which you get from the wine glass of a BAD bigwig at the BAD Bistro. (when you use the fingerprint, slide it left and right at the door) (see related question)
There is no key on Spy Island. The "vault" holding the first spy has a large hole in its ceiling. The door at the BAD hideout (satellite control station) is opened using a fingerprint from the BAD Bistro. (see related questions)
With the goggles to see the lasers, all you need is the fingerprint from the BAD Bistro to get into the satellite control center to the right of Toupee Terrace. (see related questions)
Get the fingerprint from the B.A.D. Bistro. With that and the Ultra-Vision Googls, you can enter the BAD Hideout to the right of Toupee Terrace. (see related question)
Get the fingerprint from the BAD agent at the Bistro, and use the goggles to get into the BAD hideout to the right of Toupee Terrace. (see related questions)
To complete Spy Island on Poptropica, rescue each of the 3 missing spies (in order) and acquire the spy items and the fingerprint from the Bistro. Then you can enter the BAD hideout to the right of Toupee Terrace. (There are complete solutions at both of the related questions.)
Besides the fingerprint from the Bistro, you need the Ultra Vision (laser seeing) goggles from the 3rd rescued spy, along with the three clues to the passcodes. (see related questions)
Using the decoder and the letter code, which is L=F, the word LOTMKXVXOTZ translates as "fingerprint", which is what you need from the BAD Bistro. (see the related question)