Helicopters can't fly, they're just so ugly the earth repels them
Ive also used,
" Helicopters dont fly, they just beat the air into submission!"
and "how many birds do you see with wings going round in circles?"
some i have already used, both in quick sucession
" what is that?" followed shortly by "F
uck that was close!" turned out to be a pidgeon at 4000Ft, i still dont know how he flew through the prop arc and didnt hit any blades!