Do you have children? Make them unpack some stuff. If you can convince them you are all playing a game, they will be more likely to happily help you. If not, bribery helps with them, too.
Are you unpacking alone? Invite some friends over instead. Once they arrive, explain you were in the middle of unpacking and can't do anything fun until it is done. At this point, your friends will either A) leave you and come back later, or B) offer to help. Let's keep our fingers crossed for option B!
If you can turn the whole thing into a drinking game, you can make it a fun night. Furthermore, if you are a female with male friends, it is likely your male friends will help anyway if they believe there is a chance they will get to unpack your underwear. Little do they know, you already unpacked all that before they arrived. Oh well. Just don't mention it to them until the unpacking is over.