What one's friends up there on the sanctuary moon are walking into, as is one's Rebel fleet. Generally characterized by allowing the Alliance to know the location of the shield generator, and the said shield generator being safe from one's pitiful little band, due to the fact an entire legion of another's best troops awaits them. Coincides with the deflector shield being quite operational when one's friends arrive. Also occurs when one has enemy ships in Sector 47. Often known to take place when that blast comes from the Death Star, leading one to believe that thing's operational.
Less commonly, a trap can refer to when the Force is with someone, but they are not a Jedi yet, and a second party wishes for one to join him, and together they can rule the galaxy as father and son. This type is generally announced by one's unknown sister as she is taken away by a bounty hunter. In addition, a trap can also refer to when one senses Count Dooku, to which the other replies, "I sense a trap." In these cases, the next move is to spring the trap. These two types are becoming increasingly rare, subsiding to the first type mentioned.
Controller: Admiral, we have enemy ships in sector 47.
Admiral Ackbar: It's a trap!