Honestly, for me it's the spear tackle/drop. Can't remember which match it was that I watched so far this week (may have been one from last weekend even), but the player picked up a guy without the ball (he had passed it), and practically drove him into the ground. Even the announcers said how stupid it was in light of the recent events in rugby league. And while I do understand that sometimes momentum can be part of the problem (especially with legs flying up in the air), there's no call to just drop a player when you obviously know he's in a bad body position in relation to the ground. And it's especially dumb because it draws a big penalty, and is usually quite noticeable (by the fans, players, and officials) - it's not something that a player is likely to get away with on the sly. So why risk it? Why get sent off for 10 - or worse, the entire game - just because you feel like disregarding major safety issues?
It's just dumb, dumb, dumb.