"Overwhelmingly Large Telescope": https://en.m.wikipedia.org/wiki/Overwhelmingly_Large_Telesco...
The GBT monster, the king of the telescopes at the Green Bank Observatory in West Virginia -- I always think of it as the "Great Big Telescope": https://en.m.wikipedia.org/wiki/Green_Bank_Telescope
A radio telescopes, sure, like the Very Large Array... but the next such instrument up is simply the "Square Kilometer Array", reflecting (!) the total area of all if the array elements.
(I lobbied for naming it the SRSLY, but these international consortiums can be a tough audience to calibrate; they were sick of me by the end of the conference.)
We need Douglas Adams to name a few of these.
And then, the SKA was split in two: half in Australia, and half in South Africa.
So it didn't hold up at all, but at the time, it was fun.
BBT - big beautiful telescope
SHT - seriously humongous telescope
WTF - wide-aperture telescope fleet