a naked lady
okay, now imagine this
its an alternate history.
Poland is able to smoke the soviets in their war, as well as annex lithuania. In turn, Germany is granted the polish corridor they wanted.
Germany still goes NAZI and still wants to annex Poland cause of the NAZI thing.
The Soviets are changed by their loss in the war. Not only do they withdraw from international politics (and thus, never sign the molotov-ribbentrop pact) but they also utterly hate Poland. The Soviets openly desire to annex poland, and begin arming for that. In fact, the Soviet-Polish war never officially ended, it was only stopped by a cease fire.
History basically continues as we know, going right up to the effective annexation of Czechoslovakia. However, Germany does not invade Poland in September of 1939.
WW2 starts when Germany invades Denmark and Norway on April 9th 1940. Germany would go on to invade France and Yugoslavia, without invading Poland.
All this time the Soviets have been arming, ready to invade and annex Poland, while Poland has been cut off and surrounded.
Finally, in mid 1941, Germany invades Poland.
Poland is fully aware that a NAZI victory means genocide.
Poland is also aware it is losing, and losing badly. There is simply no way Poland can stop Germany.
So the leaders of Poland decide on a plan.
They will surrender
To the Soviet Union
See the Soviets have a massive army, just itching to march into Poland. They may be Stalinist, but they are no NAZIs. Poland agrees to become the Polish Soviet Socialist Republic, and as a member, allow the USSR to re-draw it's internal borders at a whim. In return, the Soviets immediately bring in their military to defend their newly annexed territory from it's German invaders, catching Germany off guard.
By surrendering to another country, Poland is able, in the long run, to defeat the one they are truly at war with, even if it costs them their independence.