The term refers literally, to a bear trap, a snag that will prevent some from following Christ, the One Who calls us to submit to Him and part with our old dependencies on the conventions of a dying world.
Part of the trap consists of the Christian's celebration of good news won in such an ugly way, via execution of God-in-the-flesh on a cross.
Ugly too, is the Gospel's call for us to accept that our sins are what killed Jesus Christ and to accept the need for our old sinful selves to be crucified through repentance so that the new people God wants to help us become may rise with Christ.
Christ calls us to accept that the beauty of Easter morning only comes through the ugliness of Good Friday.
Jan at TheViewfromHer captures this well (and shows again why she's one of my favorite writers blogging):
...Christianity is not a religion simply formed around a wise teacher. Love your enemies. Turn the other cheek. Lose your life to find it. None of these provide the catalyst to launch a world-changing faith. Take up your cross daily - who wants to rally around that? And perhaps more revealingly, Peter, following Pentecost doesn't stand up and declare "I preach this Jesus, who spoke the Beatitudes!"Amen!
No, over and over again through the book of Acts, Peter proclaims, "this Jesus, whom you put to death, and who God raised from the dead." The resurrection is the single most significant factor of the Christian faith. It's the reason we come together this weekend, with millions of believers around the world everywhere, to celebrate our "ugly" salvation. Because it is "the Good News that saves you if you firmly believe it...that Christ died for our sins, just as the Scriptures said. He was buried, and he was raised from the dead on the third day" (1 Corinthians 15:2-4).
Death isn't the last word anymore. Death has become life. Ugliness becomes beautiful. He is risen. He is risen indeed.