So.. does anybody know what's the effect that makes the note sort of bounce when it's hit?

Which mod? Can you be more specific?
List of note effect mods:
https://projectdxxx.me/script/index/id/8753982790f7568182b95d4fe4ee7a7a By Kaito Shion.
https://drive.google.com/file/d/0By52fr0mAD3HUGl0b1FDbm5VbmM/view By Sathana Sundaravej.
Or a downloadable that you put in a folder (add to PPD/img/maingame/buttons then add to cooleffect, fineeffect, safeeffect and to slide effect):
https://mega.nz/#F!E3wlnRDb!UtqNbo7IggqKBSTCUfqwdg (NOTE: rename the pic you wanna use to NOTE.PNG before adding it to the folder)

If what you meant was the cool bounce effect then these are the two options I have:
https://projectdxxx.me/script/index/id/e05a2f3676fdd1bef87cc9947ebff6b5 By Kaito Shion
https://mega.nz/#!QQYlGAyZ!YMOUiEkbV9wJkXahcNrrUlil14_VEZePbDdYIngabWA By houtaru_39

If what I mentioned above wasn't what you wanted. Then please reply with the right answer, thanks.

Thank you Neo, you're awesome(。・艸-。)-☆

No problem, and Thank you for saying that! (●´ω｀●)