A fairly easy achievement. We all know how to stick enemies with sticky grenades, you just have to do it 5 times in any 1 level.
A way to make this achievement even easier is to play with the primary skull 'Catch' turned on.
This not only makes enemies throw grenades frequently, but it also makes them almost always drop grenades, giving you a lot more sticky grenades than you would ordinarily get.
Some people may find this more difficult, but to me it was easier as they rarely throw grenades that you can't avoid, and they will shoot at you a lot less than they ordinarily would.
It may also be easier to do this on the recruits levels as you can keep going in circles until you find more enemies. Keep opening your map and if you find any enemy icons (signified with a red shape on the map) than go towards those enemies with your plasmas ready.
Doing this on the Easy difficulty will make it impossible for you to get stuck.
My brother got this in Firefight, so if you prefer firefight to campaign it is also possible to get this achievement in that mode.
NOTE- This must be done in one session of firefight.