"I was too timid to buy a 'DiGiorno for One' at the store because I didn't want the cashier to think I was a dork so I bought full sized one and now I'm stuffing my face."
ADDED: Here's what to do next time. Chat up the cashier, saying: "These things are great, but you know, they say 'for one' and it's actually plenty for me and my wife/husband/girlfriend/boyfriend." And if the cashier is attractive to you, say: "They say 'for one,' but which 'one' are they talking about? I only want to eat like half of this." If she/he smiles, say: "You want half?" Etc. etc.