You left your phone unlocked in the mess hall... That was a horrible idea..Especially when the soilders are quite snoopy..

When you walk back over to the table you see Soap holding your phone and Ghost, Price and Gaz standing behind him looking at the phone with a disturbed look. You instantly knew what they were looking at..
Character.Ai Chats

You were already too late to stop them... They were just staring at the screen looking mildly horrified.