Llevarse un chasco

[poli]

to be unpleasantly surprised?

[aleCcowaN]

Yes, it may be. It's like being deeply disappointed or be in an embarrassing situation as a result of our wrong expectations. There's in it a component of "suddenly realizing something that causes that".

[Perikles]

Yes, my dictionary has:

chasco masculino

A (decepción) disappointment, let-down (familiar); me llevé or pegué un buen chasco I felt really let down o disappointed

B (broma) joke; una tienda que vende chascos a joke shop

[AngelicaDeAlquezar]

I'd never seen the use of "chasco" as a joke. I have always seen it as a disappointment about something gone wrong unexpectedly.

[Luna Azul]

Originally Posted by poli

to be unpleasantly surprised?

"I felt disappointed" - "I was disappointed"

I have never heard it as "joke"

[aleCcowaN]

"Chasco" includes pranks, especially those which relate with deception or traps and end up with a humiliated victim, like the pluricentennial bladder filled with water over the door. What meaning was first, the sudden prank or the sudden disappointment, it's hard to tell, but it's nice to read the definition in Diccionario de Autoridades - C (DRAE, first edition, 1729):

[poli]

A common term for prank in English is practical joke.

[chileno]

Originally Posted by aleCcowaN

"Chasco" includes pranks, especially those which relate with deception or traps and end up with a humiliated victim, like the pluricentennial bladder filled with water over the door. What meaning was first, the sudden prank or the sudden disappointment, it's hard to tell, but it's nice to read the definition in Diccionario de Autoridades - C (DRAE, first edition, 1729):

Thank you for that one. I had forgotten the one about the látigo. I guess that's where "chasquear" comes from, and I wonder about "chascón" y "chasca" too.