~Makin' Bacon:
kill a heavy with the blowtorch and dance over his corpse.
~Bigger and Better:
get a sentry to level 3 in the first 60 seconds after you started building it.
~Quantum Leap of Faith:
Telefrag a spy while at least one of your buildings is sapped.
~Scratch my Back, I'll Scratch yours:
destroy an engineers building within 30 seconds of him destroying one of yours.
~Practical Problems:
get 1000 kills with the Wrench
~Pointed at You:
get 10 kills with one level 1 sentry (upgrading it before then voids this and it must be in one "sentry-life")
~Come-on Doc!:
heal 50,000 points of damage with Dispensers
Note: i love the first idea, but since it says makin' bacon... the engie has no way to burn stuff now so I threw in the possible weapon of the blow torch. hope u don't mind
EDIT: i made a pic for one of the achievements cause I was bored...