A mother-in-law wanted to test her three sons-in-law to see how kind-hearted they were. She devised a simple plan.

First, she went for a walk by the river with the eldest son-in-law. Suddenly, she jumped into the water, pretending to drown. The first son-in-law immediately jumped in and rescued her. The next morning, he found a brand-new Toyota Corolla parked outside his house with a note:
“From your loving Mother-in-Law.”

Next, she went for a walk by the river with the second son-in-law and repeated the same act. Without hesitation, he also saved her. The following morning, he too found a Toyota Corolla parked outside his house with a note:
“From your loving Mother-in-Law.”

Finally, the mother-in-law went for a walk by the river with the third son-in-law. When she jumped in, he stood on the bank, chuckled, and walked away.

The next morning, he found a luxurious BMW M5 parked outside his house with a note:
“From your grateful Father-in-Law.”