Using your neighbor's grill without their permission, even if you plan to clean it afterward, would generally be considered rude and inappropriate. Borrowing someone else's belongings without asking for their consent is a breach of boundaries and can be seen as disrespectful.
Here are some steps you can take instead:
Ask for permission: If you want to use your neighbor's grill for your party, it's best to approach them beforehand and ask for their permission. They might be happy to lend it to you, or they might have reasons for not wanting it to be used while they are away.
Offer an exchange: If you really want to use their grill and they agree to it, consider offering something in return, such as inviting them to your party or helping with a favor in the future.
Use your own grill or consider alternatives: If your neighbor is not comfortable with you using their grill or if they decline your request, make alternative arrangements. You could use your own grill if you have one, rent one for the party, or explore other cooking options like using an oven or stovetop.
Be considerate of their property: If your neighbor grants you permission, be respectful of their grill and property. Clean it thoroughly afterward, and make sure you return it to the same condition it was in before your party.
Remember, good communication and respect for each other's boundaries are essential in maintaining positive relationships with neighbors and others in your community.