My brother has a little unsolved mystery in his life. It has perplexed him for almost 25 years. I know the answer, but I won’t tell, and I hope you won’t either.

In June 1995 he turned 40 years old. Back then, 40 was a dreaded milestone, a halfway marker in life. I wanted to surprise him in an unexpected way. I mentioned my desire to my neighbor Hannah, a diva of creativity. Immediately she signed on to be my accomplice. She had supplies and tools from her custom drapery business, and I purchased other materials we would need to cover his front lawn with macabre decorations. Over the span of two weeks we painted an R.I.P. gravestone cut from a sheet of Styrofoam. We made a life-sized Grim Reaper out of dark-colored drapery material scraps. On large poster boards we painted signs that proclaimed “Going over the hill” and that urged “Honk your horn for the Birthday Boy.” I bought a bundle of 20 black helium-filled balloons to put an exclamation point on the sign announcing “Alan turns 40 today!”

We waited until 1 a.m. before parking on a side street opposite his house, then sneaked up onto his lawn with our creations. I was afraid that banging the stakes into the ground might be too loud, so we used a towel to muffle the sound of the hammer striking wood. I also prayed that the police wouldn’t see us as they patrolled Main Street, or be called by a passing motorist who might suspect we were up to no good. All remained quiet as we worked as quickly as we could. By 1:30 a.m. we were admiring our handiwork.

Car horns honking sporadically woke my brother early the next morning. He threw on a bathrobe and opened his front door. He was stunned and baffled by what he saw. Over breakfast he and his wife debated who could have been behind the ghoulish birthday greeting. The guessing game continued later that evening as the family gathered at his house to celebrate. The potential suspects ranged from my dad, to any number of his neighbors, to co-workers and tennis partners.

Everyone he interrogated flatly denied having anything to do with the deed, but they all remarked that someone had spent plenty of time to plan and execute the elaborate prank. I never came under suspicion because my brother considered me too serious-minded and knew I wouldn’t ever stay up that late for such frivolity. He figured it was a two-person job and ultimately decided it had to be his next-door neighbors. A few months later he staged a birthday prank on his neighbor’s wife in retaliation. She didn’t deserve it.

For his next couple of birthdays my brother was on the lookout for additional pranks that never materialized. In a few years he will turn 70. I already have an idea for another birthday surprise. Watch out, little brother!