When family stealthily watches their relative and a member of the opposite sex from the house windows to see what type of hug or the length of a hug given at the tend of a supposed "date".
The act of siblings watching through windows to count the seconds of a hug to determine the seriousness of an upcoming relationship.
Mama - "What, no hug? We were on hug watch for the last five minutes trying to figure things out between you two."
Sister - "I was on hug watch last night and her hug was 7 seconds and had a sway to it, I think they are getting serious."