It's rude to skip an event you promised to attend.
Tom promised to attend his friend's barbecue, but he feels ill today.
Tom wants to decide if he should go to his friend's BBQ.
Tom decides to attend the BBQ anyway, so he heads over to his friend's.
Tom tells his friend he cannot go today because he is feeling ill.
Tom gets better a little ways into the party, and he enjoys himself the rest of the time.
Tom lies down and feels better in an hour, leaving Tom wishing he'd gone the rest of the day.