I set up a loop that looked like this:
/bind ! test1
/alias test1 "+turbo;test2"
/alias test2 "+turbo;test1"

result: vendetta crashes. no bug report screen

/bind ! test1
/alias test1 "ping;test2"
/alias test2 "ping;test1"

result: V crashes, bug screen.

/bind ! test1
/alias test1 "roll;test2"
/alias test2 "roll;test1"

result: vendetta crashes. no bug report screen

You can also get an easy segfault (no crash screen) with:

/alias loop ping; loop
/loop

there should probably be a recursion limit, or perhaps also some form of tail recursion to prevent overflowing the stack.

o00 I have one!
/alias Echoloop "echo loop; echoloop"
/echoloop

crash with a bug report screen
Now bind THAT to your fire key :P