What exactly does "tally ho" mean?

I heard this tally ho in a youtube video (British). I also heard it in the movies "Jack the Giant Slayer", and "Spiderman 1". I understand it's some kind of expression or exclamation or idiom to say in certain circumstances.

I've googled for this, I just found that it is used to say a huntsman's cry to the hounds on sighting a fox, and a cry of tally ho. First, I don't get it, and second I can't find a connection between that "tally ho" and the videos I heard it from.

Solution 1:

Although (as you brought out) it may have bore a different meaning in the past, nowadays it is (over)used in movies for when people are about to jump off a high structure or cliff, and sometimes even for jumping into the fray or a dangerous situation.

It is used pretty much like other exclamations such as Geronimo! or Away we go!

As a side note: I'm not sure if people actually use the phrase in real life, or if it's just a movie trope, such as the iconic Let's get out of here! or I'm getting a bad feeling about this.