Attitude of do something silly, or get excited with things that have no sense like "prenderse", or anything that do not goes with the moment. It comes from a character of a congress who cannot miss.
When you dont follow the party:
- Hey como que se me están quitando las ganas de ir.
- We ya te ivanaste!
- La neta ,sí.
When something its really wrong:
- Ivanismo extremo.