Should I shoot my man bioliquid into my girlfriends shampoo bottle?
That sounds gross. Why do you want to fill her shampoo bottle with your bodily fluids?
So I can mess with her.
Rethink your plan. Masturbating into her shampoo bottle is disgusting and she will be very likely to leave you if she finds out that you did it.
But how will she find out?
Well she might notice that it is not the same as it used to be. It is not moral to mess with things that belong to her.