Tidus doesn't exactly tip off, but between the force that comes from above and then the buckle as Taiki scrambles for that balance, he does slide to one side - not completely coming off, but dangling with one leg nearly reaching the ground, his other hooked leg the only thing keeping him "on" (read: hanging), along with his arms on Taiki's neck.

"Ah haha...ahhh-" Woooww this is a really awkward position! "What happened?!"

He'll try... getting his legs down...! It's way easier than trying to hoist his weight up and on properly again.