The methods used for random can be different depending on how the coder wrote it, but normally a range is set for the events to fire, and the program picks a random number in that range. In this case, you step onto floor 3 and the game runs this code
To get this specific event to happen, the result needs to match these conditions -
Code:
elseif floor3 > 11 and floor3 <= 14 and hour >= 15 and hour <= 23:
To simplify it, you need to step onto floor 3 between hours 15 and 23, and get lucky enough to have the first code land on 12, 13, or 14, out of 22.
It gets more complicated though. When you get the event, you have to have built up enough points with her to unlock more.
Code:
if juliaQW['JulMilBestFrend'] >= 50:
The game then runs another random roll, which has a 33% chance of being the kiss event.
then
The only part of this that can be cheated is her best friend score. The rest is up to RNGesus.