press a, then chuck it with b or press up before it blows you to smithereens.
Call of Duty: World at War
Also, keep in mind that the pin pulls a bit faster with Allied grenades than Axis, so allied might be a good starting point for you........
MOHH2 Persona: BCKaptKrunch
Games Pwned (Sorry, Owned): Medal of Honor Heroes 2, Super Mario Galaxy, Resident Evil 4: Wii Edition, Madden '08, Mortal Kombat Armageddon, Rayman, Rayman 2, Trauma Center, Harry Potter and the Order of the Phoenix, Tiger Woods '08, Legend of Zelda: Twilight Princess, Need for Speed Carbon, Dance Dance Revolution, Wii Sports