Just as spyral mentioned it, always get everything in writing because if your gecko dies while in someone else's care you cant be sure he/she will replace it etc and is honest with egg count. I'd only do it with people I trust with a written agreement. Also another thing that is important to include in a written document is what happens if the gecko dies but its from an illness before going to the loanee, and if its from the loanee's neglect as a loanee will not want to replace your gecko if it had a preexisting condition.