What is Sumthin?
1.
a Slang word for something derived from simply the word something just with a u as the o and no g giving you sumthin; has the same meaning as something but easyier to spell
In an AIM or MSN messager conversation
"Yo dude you gotta come over & see what I got"
"what is it?"
"SUMTHIN! It's awesome just come over and check it out dude."
See