Caldari State Customs Officers has discovered the contraband which you are transporting. If you decline to hand it over or fail to respond, you will be punished for your transgressions. Do not be alarmed, while we are waiting for your response, one of our number will target, warp scramble and stasis web you - for your safety of course.

You will then have to accept their terms or face the consequence and lose your ship. Do not jettison the items, since customs will interpret that as an act of defiance and open fire. If you want to give them up, press "Yes" in the message
popup window.
If confiscation applies, the Customs officers will confiscate it. If attack applies, they will attack you.