A proffer is a totally different reason for working a G. It is helping out a colleague, not the company. You get better compensation and someone else ends up with your G day.
What about to go see your mother who needs you right now? Is that ok?
What if your support your friend in the hospital? Is that ok?
What about making it to your sister's wedding? Is that ok?
If any of those things are that important to you and you have not been able to get the time off, joker or leave for the wedding, then you are not fit to be flying anyway as your mind will not be on the job, it will be worrying about your mother/sick friend.