In all versions of the storyline, SPY Fox must have an invitation in order to gain entry to the deck party. Because he does not have one when he tries to go onboard the first time, the weasel doorman tells him to get lost.
After SPY Fox uses the Weasel Doorman talk balloon on Gilbert in order for SPY Fox to convince Gilbert to let him look at his invitation all he wishes while he is at the booth (he can't take it as Gilbert can't be convinced to letting it go and SPY Fox can't steal it without Gilbert noticing). SPY Fox must then trick Gilbert into getting something off the shelf for him to buy (all the trinkets there are too high for Gilbert to reach). While Gilbert is distracted, SPY Fox must use the SPY Putty on Gilbert's invitation in order to create a perfect copy of the invitation.
SPY Fox must give his copy to the doorman, so that he will be allowed to go to the deck party anytime he wishes.