Where can I safely crash into signs?

When I crash into the start/finish sign on Mario Circuit, it makes the most entertaining noise and doesn't obstruct my movement (and can sometimes even block Red Shells). On which other courses can this happen?

Solution 1:

After a variety of testing, here are my results:

• The signs on Mario Circuit, Wario Stadium (DS), and Neo Bowser City (3DS) [DLC2] swing when smacked. Players should veer into them at every opportunity.
• The signs on Toad's Turnpike (N64) and Grumble Volcano (Wii) can be hit, but won't budge, and you'll just make a fool of yourself.
• Signs on other courses can't be reached, though you still have to be alert when throwing Bananas, or they'll bounce off and hat you.