if someone used a "medium," for example below the "mug," and that person did something, the next person who uses that medium basically did that same thing.
if you were a guest to your friend's house and you just happened to use his mom's mug, well your mom gives your dad a bj, then your friend has just sucked your dad's cock by proxy. Another example is, if a girl co-worker has slept with 10 guys and a guy co-worker ate the girl coworker's left over sandwich, then the guy coworker just slept with those 10 guys by proxy!
Finding a mistake after spending a lot of time figuring out the issue and being in the position such that someone else has to fix it.
Person A: I'm glad we figured out the issue!
Person B: Happy to help, I am having a lot of hanae-fun-by-proxy since you are the one who needs to fix it!
A narcissisticindividual who thinks they should have the same respect and authority as a police officer because they have a friend or relative who is a cop.
That mouthy idiot Brian thinks just because his brother is the po-po that he also has authority. Typical pig by proxy.