It is not a cheat, rather a way to get the warp whistle.
You hold the crouch button on a white block for 3-5 seconds.
Kimi wa ne tashika ni ano toki watashi no soba ni ita
Itsudatte itsudatte itsudatte
Sugu yoko de waratteita
Nakushitemo torimodosu kimi wo
I will never leave you