Speaking to her party conference, Ms Foster opened her speech by explaining the prime minister’s absence.
She said: “Rather than have [Mr Johnson] with us today, we have had to send him to the naughty step in Parliament twice in this last week.”
Ms Foster made the joke ahead of demanding honesty from the Government on Brexit, as she vowed to keep opposing the current deal until changes are made.
Ms Foster demanded "honesty" from the Government after reflecting on Boris Johnson's speech to the same event last year, when he insisted he would not erect any new economic barriers in the Irish Sea.
Denouncing the regulatory and customs borders between Northern Ireland and the rest of the UK contained in the Prime Minister's deal, the DUP leader claimed it would take Northern Ireland in the "wrong direction".
Ms Foster told delegates her party had the "boldness and strength to stand up and say no when we need to".
"On Brexit, we will not give support to the Government when we believe they are fundamentally wrong and acting in a way that is detrimental to Northern Ireland and taking us in the wrong direction," she said.
"We will oppose them and we will use our votes to defeat them.
"Let me say clearly from this platform today that we want to support a deal that works for the whole of the United Kingdom and which does not leave Northern Ireland behind.
"But without change, we will not vote for the Prime Minister's agreement."It would be bad for Northern Ireland economically and will weaken the foundations of this great United Kingdom.
"We have been clear and honest with the Government throughout this process and we expect the same in return. The customs and consent arrangements must be revisited and a one-nation approach adopted.
"We worked intensively with the Government over recent weeks to try to reach a fair and balanced deal. We were not seeking a perfect deal.
"No such deal exists. We were seeking a deal which delivered Brexit without erecting barriers to trade.
"Dublin and Brussels belatedly reopened Mrs (Theresa) May's deal having rigidly refused to do so. Having told us it could not be re-negotiated it was, and I encourage the Prime Minister to do the same again."
The DUP leader also made clear her party could not live with the proposals for Stormont to give consent for extending the post-Brexit arrangements by way of a straight majority vote, rather than with the backing of a majority of unionists and a majority of nationalists.
"The one-sided approval mechanism for the Assembly takes no account of powersharing," she said.
"Indeed, it would lead to Sinn Fein, the SDLP and the Alliance Party ganging up to render unionist votes irrelevant. If you believe in the principles of powersharing then those principles must be enshrined in any deal."
Ms Foster made reference to Mr Johnson's oft-repeated remarks at the 2018 DUP conference as she opened her leader's address on Saturday.
"It is almost impossible to believe it is 11 months since we last gathered at our conference," she said.
"In that time much has happened - we have fought, and won two elections, we have continued to strive to get a sensible Brexit deal; the United Kingdom has a new Prime Minister, and rather than have Boris with us today we have had to send him to the naughty step in Parliament twice in the last week.
"Colleagues, it was Harold Wilson who coined the phrase that 'a week is a long time in politics', but in the era through which we are living a day seems a long time.
"But while that may be the case one thing remains certain - this party continues to stand strong for Northern Ireland."