The answer to this joke/riddle is: Give him screws (replace the nails with screws).
See more monster jokes on the link below:
Halloween Party Jokes and Riddles
Many people shy away from telling jokes because they once told one that fell flat or they are afraid of appearing silly or of offending someone. Read Likehack.org's tips on how to tell a good joke.
The Huffington Post has listed 10 Practical Jokes Your Significant Other Will Hate You For. Unless you want to get unceremoniously dumped or endure the silent treatment for weeks on end, don't try any of the pranks on your significant other.