They only tell you that because they don't want to sleep with you, I haven't had that problem so I can't say It makes me feel angry.
Is it really your business though?
You seriously need to find something more important to be angry about. How do you feel about people who claim to like coffee but sometimes drink tea?
Why? How is this your problem?
Why angry? It's none of your business who other people choose to sleep with, or if they change their sexual preferences on a daily basis.
Why angry? Is this a cause for anger? Do you anger a lot over trifles? If you are not in a relationship, it really doesn't matter at all to you, does it? If you are in a relationship in which you pledge fidelity and you don't honour it, then yes, there might be causes of anger around this, but no more so than with infidelity among heteros or any other sexual orientation. If you get angry at something like this you will probably not live to old age.
What business is it of yours? There are no rules that say lesbians can't sleep with men or that gay men can't sleep with women. Many do and it doesn't change their sexuality.
What some else is doing that is their prerogative that you cannot control invokes anger in you? Let's see how long your sanity last while they will still be doing what they do.
Is there an actual question in there somewhere
How is it hypocritical? Lesbianism is not an ideology one has to stick to; it's just the state of being a woman who is only sexually attracted to other women. If a lesbian decides to have sex with a man for whatever reason, that's entirely her choice as it's her body. Granted, I think they're more likely homoflexible or gay-leaning bisexual than totally lesbian, but I'm sure there are some 100% lesbians who just do it for the physical feeling just as there are gay men who sleep with women and straight people that sleep with members of the same sex on occasion to experiment or just for fun or whatever their reason. It doesn't mean they're hypocrites, just more fluid and open in their sexuality.
they are this glorious thing known as bi. or pan
According to a recent study, girls are ranked the following when it comes to sexual-orientation.
Straight
Bi-Sexual
Lesbian
When it comes to men they are ranked by the following:
Straight
Gay
Bi-sexual
As you can see, girls are more likely to be fluid it terms of experimenting between the two genders.
Problem is that so many people think a person is either straight, gay or lesbian, when a whole lot more people than are gay are lesbian are actually bisexual and enjoy sex with both sexes. But people label others as "gay" or "lesbian" and seldom as "Bi".
There must be some benefits to be claimed by pretending to be a deviant these days so some will be one thing one day and something else another day.
They are bisexual you stupid.