Because he can see the D
AY E! I O U edit: added Y
In his briefcase!
Because he always takes a Pik-at-chu
They always get stuck at "C".
Because they lost an I.
They picked random letters out of a hat. C.... eh? N... eh? D....eh?
The letter D.
Add the letter G and it’s “gone”!
By hare (air) mail.
Because it's mage tipping berry ready for us. Obligatory edit: very easy for us