Two men carrying two canoes tied together (portaging) in a heavy rain . . .

"We should have had enough brains to bring our umbrellas!"

At first glance I could not see what was funny about this cartoon as canoeing is not something I do. But then I realized, two men, two canoes. . . normally when portaging a canoist or kayacker carries their craft overhead. They would have had their "umbrellas"!