Soft lob
A set up for a joke so obvious that pretty much anyone could go for it. Analogous to an easy pitch that anyone could hit out of the park.
He: So we're having fish tacos tonight. I've never tried fish tacos before.
She: Where were you last night?
He: Oh. Right. I guess that was a pretty soft lob, looking back on it.
She: Where were you last night?
He: Oh. Right. I guess that was a pretty soft lob, looking back on it.