In the prologue before The Friar's tale, he and The Summoner bicker--each one loathing the other's existence. I found the the Friar egotistical and condescending at times but that only made him a more lively character. When these two (Friar and Summoner) go at it, our Host came to the rescue, officiating over their arguing and efficiently officiating the telling of the tales. Those three were highly entertaining, which just goes to show you how brilliant Chaucer was at character interactions.
The Friar tells a tale about you guessed it, a summoner; one who does the lowest of jobs, administering summons and questionable justice on behalf of an archdeacon. He spares no expense and describing the summoners many sins, including extortion. The summoner is on his way to collect money from old woman when he meets the devil disguised as a yeoman. The summoner befriends the devil and the summoner informs him of his next jaunt to meet the old widow. When the summoner arrives and issues bogus charges to the widow, the old bag curses him, stating something like "may the devil take you." And then the Devil did just that--took the Summoner straight to hell. That's the short version of that tale.