Mush mouth is a particularly interesting oral sex technique involving crackers (typically saltines but anything dry will work). It is performed by chewing up enough crackers to render one incapable of speaking clearly, receiving a load in the mouth, mixing it all together, then slowly pushing it out of the mouth to run all over the face and make a gunky mess.
man: oh baby here it comes.
woman: mmmfff mff mmm mm.
man:open wide. ohhh yeah...that's a pretty mush mouth!