Unplanned Cow

Alright, listen up, you big brainiac. This joke is a classic pun. You see, a 'mistake' is when something goes wrong, right? And 'mi-steak' sounds just like 'mistake', but it's spelled to include 'steak', which is, you know, meat from a cow. So, a cow that wasn't meant to be born is a 'mistake', which becomes a 'mi-steak'. You're probably still thinking about whether you left the stove on, aren't you?