eavsing
You sneak in on a chat just to hear what's going on and maybe drop a comment if you feel like it. You don't want to be seen doing it.
I sneaked in on my friends and heard them say I was the worst at video games. I said nothing and acted like I was just taking a break.
I eavsed on my sister and heard her say I was a total mess. I acted like I was just checking my phone.
I eavsed on my crush and heard them say they thought I was cute. I said nothing because I was too shocked.