An easy one for horror fans.

There was this horror/thriller film I saw as a kid. I’d like to see it
again, but all I can remember is the ace last scene:

A man was at this lady’s house to drink some tea. She knew he was the
bad guy, so when she went into the kitchen and put poison into his
cup.

When she came back out, she picked up the teapot to start pouring, but
he put his hand over his cup, and said he wanted the other cup
instead. So she swaps cups, and pours the tea.

He starts drinking, and is perfectly fine. He stares at her while she
hesitates to drinks. Eventually she does, and she sits there shaking.

He smiles, but a few seconds later his smile disappears as the poison
takes effect. The lady stops shaking and smiles instead. It’s then
that he realises that she knew he would insist on swapping cups, so
she had put the poison in her own cup.

What is the name of this film?

Greetings markabe!

You're thinking of the 1976 film "The Little Girl Who Lives Down the
Lane."  Jodie Foster was the devious little tea maker!

imdb.com entry for the film:
http://us.imdb.com/Title?0074806

It looks like the video is currently out-of-print, but you can get
used copies of it on eBay:
http://search.ebay.com/search/search.dll?MfcISAPICommand=GetResult&SortProperty=MetaEndSort&ht=1&query=The+Little+Girl+Who+Lives+Down+the+Lane

This isn't part of your question, but I want to plug a made-for-TV
movie from the same era.  If you get a chance, watch Bad Ronald
(1974).  It's another creepy mid-70s horror/thriller film that is
entertaining:
http://us.imdb.com/Title?0071186

I hope this information is helpful.  If you would like for me to
clarify any part of my answer or further research your question,
please let me know before issuing a rating.  Thanks!


leep-ga


search strategy used:
personal knowledge of films

What a fast answer! Impressive.