I grew up around Foster’s Freeze (a California tradition, started in La Brea).
http://www.fostersfreeze.com/soft-serve_shakes.html
It’s one of the very few fast-food places where you can get a malted milkshake (Carl’s Jr. is the other one).
A $7 milkshake is a bit steep. Must have ordered a large one.
In Pulp Fiction, Vincent Vega (the resurrection of John Travolta's acting career) was astonished that his date who wasn't a date, Mia (played by a super young and hot Uma Thurman) had ordered a $5.00 milk shake.
Now $5.00 milk shakes are pretty much routine, you can get them just about anywhere except McDonald's.