Dirty Tiger, Crazy Frog (1978)
Crazy Frog (Sammo Hung) comes across the 'Invincible Armor', thought lost for decades, and manages to steal/swindle it out of the old lady that owns it. Dirty Tiger (Lau Kar-Wing) is employed to bring him back, but once he learns of the armour he comes up with a different plan. He's not the only one - once word of the armour's discovery is out, every man and his monkey seems to want to get it. The most serious contenders are a bandit family led by a white-browed former Shaolin Monk. The movie is a non-stop series of crosses, double crosses, thefts and swindles as everybody tries to get the armour or at least some money out of the situation.
This is one of those movies where everybody is a thief and a conman, and the difference between the good guys and bad guys is mainly their degree of stupidity - though by this criteria, Crazy Frog would probably be the worst of the lot :) The different plots & subterfuges employed are quite amusing - mainly due to their stupidity. There's quite a bit of kung fu employed, with Sammo and Lau Kar-Wing both showing off some great skill. Most of the fights are played for laughs though, with more "gimmicky" choreography than realistic fighting techniques. All very much in the old-school Peking Opera style too.
Not the best old school movie, but not a bad one. Definitely worth seeing if you like Sammo and Lau Kar Wing.