Substituting, do they watch?

Alright I plan on substituting my urine with some of my girlfriends. This is for a pre-employment drug test at a crummy place. I'm surprised they even drug test. Anyways, I have 2, 1.75oz bottles I was planning on filling, is that enough?
Do they watch and or listen to you pee? If they watch how do you empty the bottle without them knowing?

uhh u really only need a lil bit

i used to fill up two visine bottles

worked fine for me

and everyplace is different as for watching