From the Rules:

Allowed commands/bindings: -Any bind that is accessible from the menu -sv_player_funnel_into_portals binding (checkbox in the menu) -toggle_duck binding (default controller bind) -cl_showpos 1 -r_drawviewmodel 0 -binds for sensitivity -save/load on one key binding -save, fps_max [fps], load on one key binding -custom named save binds -demo plugin related binds

ent_fire commands in general are not allowed, because they allow you to spawn and do all kind of things. Fizzling Portals is also not a default mechanic in the game.

You're probably thinking of the Minecraft Portal mod based on your tweet history.

actually the flashgame had that exact behaviour on the exact button.