2 variants

Question: How can a man get across the river to the bus station, if the bus leaves in five minutes?
Answer: He runs over the ice, because it’s winter.
Archive reference: RKM, KP 17, 39 (2)
Location: Mär Märjamaa Kk, 7. kl
Date: 1992
Subject: a man across the river
Question: Here is a lake and here in the middle of the lake there is a prison. Here is an island. How can prisoners escape?
Answer: In winter there’s ice.
Archive reference: RKM II 347, 221 (25)
Location: Räp
Date: 1980
Subject: prisoners are escaping