a sonny gun is when emo kids make pretend guns with their fingers and pretend to kill their friends with the "weapon". usually do it to look so freaking Xcore. When using a "sonny gun" emo kids usually like to make sound effects when they "shoot" their friends with it, such as: BANG BANG!!!.
this came from the song: "kiss me, im contagious" from the band: "From First To Last". Emo kids tend to favor this band. Since emo kids like to copy the trends and fashions of their favorite bands, the emo kids stole this gun trend from From First To Last's lyrics in "Kiss me, im contagiuos". when you see an emo kid with a sonny gun, you should shoot him/her with a REAL gun.
samantha: look at those annoying emo kids use the sonny gun.
joe: ewww, yeah. such attention whores.
samantha: well...i guess we brought it upon ourselves. i mean, we ARE at the mall =/.
joe and samantha: EMO TERRITORY FOR SONNY GUN FIGHTS.