A “Deez nuts” joke involving two nuts (fasteners) welded together to resemble two testes.

Plate nuts are really useful, used them on vacuum systems in grad school. Once threaded by hand, you don’t need a wrench for the nut end since the other nut prevents the plate from rotating. Made star-pattern tightening a large flange with cramped access relatively easy.

Can’t believe I went through years of grad school with puerile labmates and never once heard (or used) that phrase…