Cisco IOS IKE pre-shared key error message

I found out if your IPSec tunnel's preshared key is wrong on Cisco IOS routers, the message that it shows is:

%CRYPTO-4-IKMP_BAD_MESSAGE: IKE message from 173.33.140.143 failed it ^s sanity check or is malformed

Talk about cryptic messages! Not very helpful, but now you know if you see that message, check your preshared keys!