tape the cap shut. wrap the bottle in lots of sarah wrap if you don't have access to a vaccum sealer. use lots of bubble wrap and fill the empty spaces left if the box with packing peanuts. the people at the counter -- if using usps -- will ask if you are shipping anything illegal like alcohol, fireworks, etc. say "no". then they'll ask if there is anything breakable in the box, you want to answer "yes" otherwise they'll punt your box around in the back. if they still ask what it is, tell them it is homemade olive oil.