Applejack's plan to confess her long hidden feelings to Rainbow Dash is elegant in its simplicity. A bottle of liquid courage and some privacy. Entire generations of ponies have been conceived from similar circumstances. What could possibly go wrong.

What Applejack doesn't know is that Pegasi are featherweights. When her feelings don't get a straight answer. (Pardon the pun) Applejack runs off on a drunken rampage.
With the help of their friends, and grievous misuse of a grizzly bear, the estranged pair manage to avoid alcohol poisoning and Twilight Sparkle gets to avoid murdering anypony for interrupting her precious story time.
And Berry Punch was there and she was the greatest heroine of all. The end.