Using ² to duplicate a word
This is a bit of an old style slang which I think was popular in the late 90s.
There is a ² added to a word to duplicate it. It kinda works like the 々 mark as slang but for the entire word.
In the following picture for example it means すっごくすっごく:
And in the following one it simply means めちゃめちゃ: