There are lots of different variations of what it could mean. Not one definition is widely used on Twitter. You should ask the person you seen use it what it means.
Tosho is a user on Twitter.
RTMI officially on twitter means ReTweetMyIsh
Where Will You Be At.
do you mean his address for twitter ? his twitter is @STEFANABINGDON
It mean Sunday follow .....
It refers to a Twitter application to upload music.
The location on twitter is usually the place where the page's holder lives.
It refers to the Twitter PT Challenge. See the related link.
retweet
Background.
Fight them
Fashion's Night Out