In SSMS, open three sheets and run sheet 0. Then run sheet 1 and 2 within 10 seconds of each other.
Remember to do rollbacks in sheets 1 and 2 after failure.
-- sheet 0
CREATE TABLE t1 (i int);
CREATE TABLE t2 (i int);
GO
INSERT INTO t1 VALUES (1);
INSERT INTO t2 VALUES (2);
GO
SELECT * FROM t1;
SELECT * FROM t2;
GO
-- sheet 1
BEGIN TRAN
UPDATE t1 SET i = 10;
WAITFOR DELAY '00:00:10';
UPDATE t2 SET i = 20;
COMMIT TRAN
-- rollback
-- sheet 2
BEGIN TRAN
UPDATE t2 SET i = 22;
WAITFOR DELAY '00:00:10';
UPDATE t1 SET i = 11;
COMMIT TRAN
-- rollback