Yeah, that is not going to be a good bet at all.

In the early 90's I played BJ in Atlantic City for 3 years hardcore after I already knew the game very well and thought I saw it all. Took a trip to Vegas and was at a $25 min. table where a lady had $200 on a bet and got a BJ. BUT, she decided to try her luck and double down. Some casinos won't let you do this but most should since it's a real sucker bet. Anyhow the dealer showed a 4 and the lady doubled and got a 10 for 21 (not BJ). Can't remember if the dealer made a hand or busted but if the dealer got 21 it would be a push.

I thought to myself wow, can't believe I would ever live to see that. It is one thing to see someone split 10's vs. a dealer 5 or 6 but to double a BJ that already pays 3 to 2 was mind blowing.