It isn't a credit card you use to open the laundry room door, it is a Joshie Club card that you get from Rowley. To get the card, you have to return the Twisted Wizards CD after you have played the game. This is tricky because the game moves too fast during your time at Rowley's house (second house left of Greg's).
The General Process:
Once you have chased Manny to the school, recover the Twisted Wizard guide from Greg's locker. Take it back and click Greg, then Examine the guide. Then click on the TV Greg is using for a monitor and you can play Twisted Wizards. Beat the game using the Easy Mode (click the Wizard before clicking Start).
When you try to return the CD to Rowley, his dad won't let him out, or you in. Go to the right and jump on the dad's (Mr. Jefferson's) car, setting off his alarm. Before he comes out, *very quickly* jump behind the bush to the left of the front door (Hide). As he comes out, quickly click the door to enter before he comes back. This may be a bit hard to accomplish due to slow responses from the game server.
You get it by giving the Twisted Wizard game to the Wimpy Kid's friend that lives next to him.
the card is in gramma house if not in leisure towers
you have to get this card that opens the door. You get the card from Greg's friend.
Use the Fan Club Card.
Once you get the Joshie Card, you can put it in the slot to open the Laundry Room.
Wimpy Wonderland is an island on Poptropica.
Use it to open the laundry room door at Gregs house.
give Rowley his game he'll give you a credit card use it in gregs house turn of the basement get sweetys bowl go in gregs garadge
At the left end of wimpy wonderland.
where is the twisted wizard guide in wimpy wonderland
there is no fan club on wimpy kid island. he gives you the card to unlock the laundry room in Greg's house.
You have to get the Joshie Club Membership Card from Rowely then use it on the door.