A great spot for this achievement is right away after you've met Jeff. Larry will toss a bottle to show you how Jeff works and Jeff will come running out. Step forward a bit onto the broken catwalk and use the Russells to grab a bottle from the ground below you. Then drop that bottle directly beneath you to bring Jeff right underneath you. Stand here for 10 seconds with him directly below you and the achievement is yours. It may be a good idea to also grab a second bottle from down below in case he starts walking away.