Can you solve the $20 riddle? ft SMBC Comics' Zach Weinersmith

the second riddle has loopholes, imo

rule: if the statement is false, 10$ go from V (victim) to C (cheater)

option 1:
this statement simply has no value at the point when it is stated, so none of the two knows what to do.
if V decides to give 10, the statement turns true and therefore, V must take back the 10. then, they both end in an endless loop which will lead to their deaths.

option 2: 
the statement becomes irrelevant after the first transaction because it only states "you will give me 10 or 1000". it doesn't say "i will end up getting 10 or 1000". so, after transfering the first 10, the statement is "used up" and its value no longer changes.

option 3:
V gives C another 10$ bill from his own pocket. this will make the statement true without giving one of the bills back.

option 4:
V gives back 20, making the statement false. he gives back the required 10, thereby following the rules, but by giving back too much, the statement stays false and they do not end up in a recursion.

the correct answer of C should have been: 
"i will only agree if your statement will not cause a recursion"

the correct statement of V should have been:
"this deal will end once i have gotten one of these 10$ bills back or you paid me 1.000.000$"