I was just about to do that
When someone says they were going to do something, but they're just trying to look like they're not the biggest slouch in the group, even though they still didn't do a thing
'I was just about to do that', said by the person who didn't move from the couch
'I was just about to do that', said right after I did it myself
'I was just about to do that', said while they were still eating chips