A passenger train is creeping along, slowly. Finally it creaks to a halt. A passenger sees a TT walking by outside. "What's going on?" she yells out of the window.
'Cow on the track!" replies the TT'.
Ten minutes later, the train resumes its slow pace. Within five minutes however, it stops again. The woman sees the same TT walk by again. She leans out the window and yells,
'What happened? Did we catchup vvith the cow again?'