1) challenge.mw3.[COLOR="#FF0000"]ch_infected[/COLOR].name = Get knifed by an enemy who is wearing the “Infected” title

Minimum required level to complete: Level 4

Emblem unlocked: None

Title unlocked: The "Infected" title



2) challenge.mw3.[COLOR="#FF0000"]ch_plauge[/COLOR].name = Knife an enemy who is wearing the “Transfer” title

Minimum required level to complete: Level 4

Emblem unlocked: None

Title unlocked: The "Transfer" title

 

3) challenge.mw3.[COLOR="#FF0000"]ch_no[/COLOR].name = Kill an enemy while he is cooking a frag grenade

Minimum required level to complete: Level 4

Emblem unlocked: None

Title unlocked: The "No." title

 

4) challenge.mw3.[COLOR="#FF0000"]ch_ renaissance[/COLOR].name = Kill 3 different enemies with 3 different guns in 1 life

Minimum required level to complete: Level 4

Emblem unlocked: White man's head

Title unlocked: The "Kleptomaniac" title



5) challenge.mw3.[COLOR="#FF0000"]ch_ sidekick[/COLOR].name = Get 3 kills in 1 life with your secondary weapon

Minimum required level to complete: Level 4

Emblem unlocked: Eyeball

Title unlocked: The "Sidekick" title

 

6) challenge.mw3.[COLOR="#FF0000"]ch_avenger[/COLOR].name = Avenge a teammate’s death

Minimum required level to complete: Level 4

Emblem unlocked: Black man's head

Title unlocked: The "The Avenger" title

 

7) challenge.mw3.[COLOR="#FF0000"]ch_theloner[/COLOR].name = Get a 10 killstreak with no killstreaks selected

Minimum required level to complete: Level 4

Emblem unlocked: 2-D supermario character 

Title unlocked: The "Behind Enemy Lines" title

 

 challenge.mw3.[COLOR="#FF0000"]ch_radiationsickness[/COLOR].name = get killed by an enemy M.O.A.B.

Minimum required level to complete: Level 4

Emblem unlocked: None

Title unlocked: The "Toxic" title

 

9) challenge.mw3.[COLOR="#FF0000"]ch_nuke[/COLOR].name = Call in 250 (8 tiers) M.O.A.B.s

Minimum required level to complete: Level 4

Emblem unlocked: None

Title unlocked: None

 

10) challenge.mw3.[COLOR="#FF0000"]ch_hijacker[/COLOR].name = Highjack 200 (3 tiers) enemy crates

Minimum required level to complete: Level 4

Emblem unlocked: Open treasure chest

Title unlocked: None

 

11) challenge.mw3.[COLOR="#FF0000"]ch_livingdead[/COLOR].name = Survive Final Stand

Minimum required level to complete: Level 32

Emblem unlocked: None

Title unlocked: The "Living Dead" title

 

12) challenge.mw3.[COLOR="#FF0000"]ch_martyr[/COLOR].name = Get a kill from your Martyrdom deathstreak grenade

Minimum required level to complete: Level 51

Emblem unlocked: None

Title unlocked: The "Martyr" title



13) challenge.mw3.[COLOR="#FF0000"]ch_clickclickboom[/COLOR].name = Get a kill with C4 while in Final Stand

Minimum required level to complete: Level 69

Emblem unlocked: Crazy pig head

Title unlocked: None

 

14) challenge.mw3.[COLOR="#FF0000"]ch_6fears7[/COLOR].name = UNKNOWN

Minimum required level to complete: UNKNOWN

Emblem unlocked: UNKNOWN

Title unlocked: UNKNOWN

Originally posted by Crysis

Thank you for this, I really didn't know it was that simply, if I find more hidden ones I'll post here.