Fartup is when you really to pass gas but there are too many people around, therefore you hold it in to such an extent that you feel it going back up inside you.
'Did you fartup during that board meeting? Your face turned so blue.....'
''I noticed that your eyes teared up on that long elevator ride, you must have had a fartup".
'That chilli i ate at the staff party made a major comeback. man, that fartup went so far back up inside, i could taste it when i hiccuped!!