I striped the bbcode to only what is causing the glitch

Code:
[ SIZE=2]

[ spoiler=Less Than Zero]
[/SIZE]
[ SIZE=2]
TEXT HERE
[/spoiler]

[ spoiler=PARTY]
[/SIZE]
TEXT HERE
[/spoiler]
looks like this:



Less Than Zero
Less Than Zero


PARTY
PARTY


So basically it's because you have a size tag that opens outside of a spoiler tag and closes within a spoiler tag. In other words, how you format your post is completely the point. If you didn't place a shit ton of format tags all haphazardly throughout your post, shit like that wouldn't happen.