With bipods on rifles, players can bury themselves underground, while still having vision of surrounding area.
https://www.youtube.com/watch?v=Jcd9nAgnjqI
Affects: LRR, MXM
Does not Affect: SPMG
Others not tested.
Appears to be related to the position of the bipod view. Once you change your bipod angle, it does not work. The closer to the "centre" of your bipod position, the more likely it will happen.