(Held up a small bottle of obviously-cannot-be-drunk-liquid)
'Class, do you think u can drink this?'
'No...'(some hestiating)
'Yes u can drink this! Only once.'

(Held up a self-made boomerang)
'This is a guarantee-return boomerang. If you throw this out, it will come definitely come back.
Another reason why its called a guarantee-return boomerang is becos if u throw it at your fren, ur fren will throw back at you.'