A few days ago (before the latest patch) I was in a TT game with a few friends. In a single game three different people got trapped in minion waves and were unable to move without killing the minions. It happened to me as Cho'Gath, my teammate as Warwick, and the enemy Tahm. I've seen it happen at various other times, but to see it three times in a single 30-ish minute game is a sign that things are really bad.
When it happened to me, I got encircled in a clump of my own minions fighting the enemy team's minions. I couldn't get to my ally in time to save them from an ambush, and I just durdled around trying to get myself unstuck as my ally died. The enemy Tahm tried to run past a wave of his own minions as my teammates chased him. He would have made it, but the minions closed around him, essentially creating what looked like a tiny J4 ult just around him. I didn't see exactly what happened to Ww since I was still in the teamfight he was trying to get out of, but I was in a Skype call with the guy. I'm paraphrasing here, but it boiled down to: "Wait, what? Why can't I- Ohfortheloveof- Minions, no! LET ME OUT! MINIONS! YOU'RE WORSE THAN THE YELLOW ABOMINATIONS THAT TOOK OVER FACEBOOK! RELEASE M-" An ally has been slain "^^^^ that."