diff --git a/sandbox/__init__.py b/sandbox/__init__.py
index 2bd700f..89f75ca 100644
--- a/sandbox/__init__.py
+++ b/sandbox/__init__.py
@@ -1,2 +1,11 @@
+from datetime import datetime
+
+
 def useful_function():
     return 42
+
+
+def is_towel_day(day=None):
+    if day is None:
+        day = datetime.today()
+    return (day.day, day.month) == (25, 5)
diff --git a/sandbox/tests/test_towel_day.py b/sandbox/tests/test_towel_day.py
new file mode 100644
index 0000000..2563eb9
--- /dev/null
+++ b/sandbox/tests/test_towel_day.py
@@ -0,0 +1,8 @@
+from datetime import datetime
+from sandbox import is_towel_day
+
+
+def test_towel_day():
+    assert is_towel_day(datetime(2011, 5, 25))
+    assert not is_towel_day(datetime(2011, 6, 25))
+    assert not is_towel_day(datetime(2011, 5, 26))