Take two slices of bread, put something tasty on them, slap the slices together, and you've got a sandwich, right?
Well, you may call it a "sanwich" or "samwich," and you're certainly not alone.
University of Michigan English Professor Anne Curzan recently heard someone making fun of a person for saying "samwich," and thought that wasn't very kind.
"What we have happening here is the simplification of a consonant cluster. If you think about the word 'sandwich,' you've got n-d-w in the middle of the word – and that's not the easiest of consonant clusters to deal with. For many speakers, what happens is that we will delete the 'd,' so then you've got 'sanwich.'