Grunt Playing with halo toys
From Halopedia, the Halo wiki
This easter eggs can be seen in a cinematic. On the level Delta Halo at the very beginning were you see the grunt (looks like he's playing in the dirt but isn't) look closely at the grunt and you will notice that be has a mastercheif toy and a grunt toy in his hands. (better to see if you take a picture and zoom in with a editing program. or have a modded xbox that lets you detatch the camera then freeze time and look at the grunt. or if you have halo 2 vista you the detachable cam.