Sis high hopes i just tried it two minutes ago (talking with a bottle cap in my mouth). Try it out, and you'll see that its totally crazy. If you have to talk on the phone like that, in all probability, the person will feel obliged to rush straight to your house and make sure that you never had a stroke or swallowed your tongue.
Pretending that you have a lisp just makes you laugh at yourself while talking.
Chomping chappies make you sound ''street''.
Screaming into the phone is not becoming of a muslim.
Tho, i do understand your point. I think its best to just be as official and formal as possible when talking to any man =)