what's popping

[grubsmoothie]

I just joined last thursday and I've just been vibing figuring this site out. my boyfriend helps a lot. but I keep seeing things and they're confusing me so I have just a few questions;
1) why do many people in raffles ask you to type your username? I'm not against doing it but cant you see the username in the reply anyway?
3) what the heck is a paper clip challenge