Arnold Schwarzenegger Makes Raunchy Jokes About Customs Detention

Arnold Schwarzenegger's customs detention was a serious matter that held him in Germany -- but now that he's where he needs to be ... the dude's cracking jokes, kinky ones too!

The Terminator finally made it to his big auction in Austria Thursday -- where he took the stage at the famed Stanglwirt Resort ... where he was hosting a bidding war on behalf of his Schwarzenegger Climate Initiative, with that pricey watch being one of the items.

arnold Schwarzenegger watch

Check out this video, obtained by TMZ, where AS is intro'd and comes out to address everyone in the room. The dude dives right into what happened to him at the Munich airport.

He was in a real fun mood -- 'cause Arnold basically did…