Paul said it about himself several times in 2nd Corinthians (especially chapters 11 and 12):
11:1 "I hope you will put up with a little of my foolishness; but you are already doing that."
11:17 "In this self-confident boasting I am not talking as the Lord would, but as a fool."
11:21b "What anyone else dares to boast about - I am speaking as a fool - I also dare to boast about."
12:11 "I have made a fool of myself, but you drove me to it."
The people of the Corinthian church drove Paul to use sarcasm because they questioned his authority as an apostle. Paul boasted about himself (as a fool would) to show them that he had the authority as an apostle so that they would take him seriously. There were false teachers speaking negatively of Paul and apparently there were a group of Corinthian Jesus followers who started questioning his legitimacy as an apostle.
Paul stooped to sarcasm to legitimize his ministry. Paul loved the church so much that he had to defend himself in a way that would get them to take notice. Sometimes we have to stand up to the forces that oppose God's calling on our life, even if that means using sarcasm as a weapon.
More times than not, sarcasm is a detriment to the faith and to the goodness of God, however, it is a relief to find that there is a place for it in the church when used correctly.