I second this. Your friend buys a cheap int. ticket on any carrier (but keep any visa requirements for that particular destination/country in mind), check-in ad proceeds through immigration and security to meet you in the transit area. After your meeting your friend proceeds to the gate or transfer desk of the airline and ask to be off-loaded from the flight explaing that something was forgotten at home which makes travelling in vain - and ask to be taken/directed to arrivals level to enter TH again.