[General] 'spend on doing something' aceptable?

[LiuJing]

My English teacher has this rule for us when it comes to the usage of 'spend':

spend money/time (in) doing something
spend money/time on something

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However, I frequently come across 'spend ...on doing something' pattern like this one:
Gaga gambles, shows humility at Atlantic City show - NYPOST.com

Gaga graciously thanked her fans for coming: "I know the economy really sucks right now, and you spent your money on hanging out with me on the Fourth of July, so I thank you."

Is my teacher's rule out-dated? Thank you.

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[philadelphia]

* Not a teacher

Spend money on doing something is more than acceptable, that is perfectly correct. Eg They have just spent money on improving our English.

Spend time on doing something would tend to be uncorrect - it should go differently. Eg We have just spent a couple of minutes improving our English