As they walk into their room, 3 of them, whip out some vodka, food and cigarettes and begin to make jokes about the government and be very loud indeed. The 4th one is trying to get some meaningful sleep and knowing that it would be fruitless to ask them to stop, hatches an ingenious plan. He goes downstairs to reception and asks for a cup of coffee to be delivered to the room.
“Make sure you deliver it exactly after 10 minutes starting from now”
Returning back to the room he joins his comrades midway a Stalin joke. He sits up shocked and exclaims:
“Comrades! You must not say these things! Don’t you know? They are listening to our conversations right now!”
The comrades jeer and laugh at him and say that that is impossible.
“Really? Then how do you explain this?”
He gets up and speaks into the lampshade by the beds.
“I would like a black coffee to be delivered to my room, please.”
And surely enough, in a short amount of time, a maid walks in with a cup of coffee and some sugar.
The other 3 comrades turn deathly pale and quickly turn in for the night. The last comrade drinks his coffee and peacefully goes to sleep.
Come morning the 4th comrade awakens only to find that his friends and all their belongings are missing.
Throughly confused and anxious, the man walks down the stairs to reception to enquire whether his friends had checked out earlier in the morning.
“I am afraid not sir. You see, the KGB raided your room during the night and placed your friends under arrest for ridiculing the Soviet regime.”
“B-but how come they didn’t take me?!”
“Oh, the Captain very much enjoyed your joke”
(translated from Russian)