I'm going to cancel plans at the last second
Why would you cancel your plans?
Because I thought the plans sucks and the people were lame.
It is not acceptable to purposely wait until the very last second to cancel plans. This shows disrespect and a lack of caring for the other person. If you cancel plans at the last minute, people will not want to make plans with you anymore.
I started the plans with my friends when I was drunk so I have the right to change my mind when sober.
I still don't think that gives you the right to bail on them last minute.