use crash;
db.crash.save(

);
db.crash.distinct('a.b');

This code will not only produce an error but crash the shell client entirely with the message:
Mon Oct 26 00:52:03 Assertion failure n > 0 32bit/scripting/engine_spidermonkey.cpp 468
0x65f19 0x6c29f 0xa66e0 0x9d09c 0x14a0b3 0x149d40 0x14b1ea 0x12cacb 0x11e1a5 0xdf539 0xdf490 0xdf39a 0xa20a2 0x4c49 0x5ed4 0x1b56 0x1
0 mongo 0x00065f19 _ZN5mongo12sayDbContextEPKc + 281
1 mongo 0x0006c29f _ZN5mongo8assertedEPKcS1_j + 335
2 mongo 0x000a66e0 _ZN5mongo9Convertor5tovalERKNS_11BSONElementE + 5472
3 mongo 0x0009d09c ZN5mongo16resolveBSONFieldEP9JSContextP8JSObjectljPS3 + 716
4 mongo 0x0014a0b3 js_LookupPropertyWithFlags + 881
5 mongo 0x00149d40 js_LookupProperty + 53
6 mongo 0x0014b1ea js_GetProperty + 209
7 mongo 0x0012cacb js_Interpret + 55653
8 mongo 0x0011e1a5 js_Execute + 774
9 mongo 0x000df539 JS_EvaluateUCScriptForPrincipals + 167
10 mongo 0x000df490 JS_EvaluateUCScript + 67
11 mongo 0x000df39a JS_EvaluateScript + 108
12 mongo 0x000a20a2 _ZN5mongo7SMScope4execERKSsS2_bbbi + 498
13 mongo 0x00004c49 _Z5_mainiPPc + 7177
14 mongo 0x00005ed4 main + 36
15 mongo 0x00001b56 start + 54
16 ??? 0x00000001 0x0 + 1
terminate called after throwing an instance of 'mongo::AssertionException'
what(): assertion 32bit/scripting/engine_spidermonkey.cpp:468
Mon Oct 26 00:52:03 mongo got signal 6 (Abort trap), stack trace:
Mon Oct 26 00:52:03 0x2bd6 0x939b5b9b 0xffffffff 0x93a43b99 0x93a59c50 0x94e33fda 0x94e3217a 0x94e321ba 0x94e322b8 0x6c46f 0xa66e0 0x9d09c 0x14a0b3 0x149d40 0x14b1ea 0x12cacb 0x11e1a5 0xdf539 0xdf490 0xdf39a
0 mongo 0x00002bd6 _Z12quitAbruptlyi + 374
1 libSystem.B.dylib 0x939b5b9b _sigtramp + 43
2 ??? 0xffffffff 0x0 + 4294967295
3 libSystem.B.dylib 0x93a43b99 raise + 26
4 libSystem.B.dylib 0x93a59c50 abort + 93
5 libstdc++.6.dylib 0x94e33fda ZN9gnu_cxx27_verbose_terminate_handlerEv + 433
6 libstdc++.6.dylib 0x94e3217a ZN10cxxabiv111_terminateEPFvvE + 10
7 libstdc++.6.dylib 0x94e321ba ZN10cxxabiv112_unexpectedEPFvvE + 0
8 libstdc++.6.dylib 0x94e322b8 ZL23_gxx_exception_cleanup19_Unwind_Reason_CodeP17_Unwind_Exception + 0
9 mongo 0x0006c46f _ZN5mongo8assertedEPKcS1_j + 799
10 mongo 0x000a66e0 _ZN5mongo9Convertor5tovalERKNS_11BSONElementE + 5472
11 mongo 0x0009d09c ZN5mongo16resolveBSONFieldEP9JSContextP8JSObjectljPS3 + 716
12 mongo 0x0014a0b3 js_LookupPropertyWithFlags + 881
13 mongo 0x00149d40 js_LookupProperty + 53
14 mongo 0x0014b1ea js_GetProperty + 209
15 mongo 0x0012cacb js_Interpret + 55653
16 mongo 0x0011e1a5 js_Execute + 774
17 mongo 0x000df539 JS_EvaluateUCScriptForPrincipals + 167
18 mongo 0x000df490 JS_EvaluateUCScript + 67
19 mongo 0x000df39a JS_EvaluateScript + 108
/opt/local/include/boost/thread/pthread/recursive_mutex.hpp:62: failed assertion `!pthread_mutex_destroy(&m)'
Mon Oct 26 00:52:03 mongo got signal 6 (Abort trap), stack trace:
Mon Oct 26 00:52:03 0x2bd6 0x939b5b9b 0xffffffff 0x93a43b99 0x93a59c50 0x1da24d 0x92f8f 0x9396e88f 0x9396e7a4 0x2d08 0x939b5b9b 0xffffffff 0x93a43b99 0x93a59c50 0x94e33fda 0x94e3217a 0x94e321ba 0x94e322b8 0x6c46f 0xa66e0
0 mongo 0x00002bd6 _Z12quitAbruptlyi + 374
1 libSystem.B.dylib 0x939b5b9b _sigtramp + 43
2 ??? 0xffffffff 0x0 + 4294967295
3 libSystem.B.dylib 0x93a43b99 raise + 26
4 libSystem.B.dylib 0x93a59c50 abort + 93
5 mongo 0x001da24d __eprintf + 77
6 mongo 0x00092f8f __tcf_10 + 79
7 libSystem.B.dylib 0x9396e88f __cxa_finalize + 208
8 libSystem.B.dylib 0x9396e7a4 exit + 33
9 mongo 0x00002d08 _Z12quitAbruptlyi + 680
10 libSystem.B.dylib 0x939b5b9b _sigtramp + 43
11 ??? 0xffffffff 0x0 + 4294967295
12 libSystem.B.dylib 0x93a43b99 raise + 26
13 libSystem.B.dylib 0x93a59c50 abort + 93
14 libstdc++.6.dylib 0x94e33fda ZN9gnu_cxx27_verbose_terminate_handlerEv + 433
15 libstdc++.6.dylib 0x94e3217a ZN10cxxabiv111_terminateEPFvvE + 10
16 libstdc++.6.dylib 0x94e321ba ZN10cxxabiv112_unexpectedEPFvvE + 0
17 libstdc++.6.dylib 0x94e322b8 ZL23_gxx_exception_cleanup19_Unwind_Reason_CodeP17_Unwind_Exception + 0
18 mongo 0x0006c46f _ZN5mongo8assertedEPKcS1_j + 799
19 mongo 0x000a66e0 _ZN5mongo9Convertor5tovalERKNS_11BSONElementE + 5472