Looks like it is the name of a FORTRAN subroutine[1] from MTS (Michigan Terminal System) that somehow creeped into our dictionary files. Now you can buy hoodies with "1 <3 PGNTTRP" prints and watch videos like that above, because of bot produced content.

[1] https://deepblue.lib.umich.edu/bitstream/handle/2027.42/7958...