The pirate flag emblem is currently unknown and not verified... but the skull and bones emblem is when you get twenty game winning kills.
See related links.
You unlock it by getting to 10th Prestige.
2nd prestige
A website that will answer this is:callofduty.wikia.com/wiki/Callsignsit helps alot
25 kills with cooked frags.
Ten Tactical Nukes to unlock the emblem.
Kill 2 or more enemies with a single frag grenade, 50 times.
by killing someone with a ten or more killstreak that's for the emblem
Holt theres a emblem like that? look on Google
Get hacked
Kill 300 people who are still dazed by a stun grenade. You must be prestiged to unlock this.
because your clan has to be like lvl 5 or something for the emblem to take effect.....once ur clan is a high enough lvl the emblem will start to appear