This isn’t a prank, just some wording that could be taken two different ways. (Had he meant it the other way I would not be posting this.)
The Yeshiva for some reason ended a few days later than most other yeshivos but they were understanding if guys needed to leave early to get a position at camp.
One popular guy took off those last few days every year until 12th grade when the Rosh Hayeshiva told him that they needed someone charismatic to speak by the graduation so he couldn’t leave early. He was very disappointed since the camp told him that they would have to replace him if he couldn’t be there for the whole summer.
So, the guy is speaking by the graduation. He gets up to the gratitude part of the speech where he thanks his parents, teachers… “And, last but not least, I owe a very special thanks to the Rosh Hayeshiva, who if not for him I wouldn’t be standing here right now…”