Definition by Wonder Me!:
Partial agonists actually can block the effects of full agonists when dispersed together.

Clinical examples:

Nubain = partial agonist
Oxycodone = full agonist
=> Too much nubain => less receptors for oxycodone to bind => oxycodone can exert its effects that it usually can in the absence of nubain => reduced pain relief (1)





References:
(1) https://books.google.com/books?id=AniUCgAAQBAJ&pg=PA327&dq=oxycodone+nubain+agonist&hl=en&sa=X&ved=0ahUKEwjEhqO56fHLAhWEwYMKHUBiAW8Q6AEIHDAA#v=onepage&q=oxycodone%20nubain%20agonist&f=false